Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: lester_wareham on August 04, 2005, 04:26:37 am

Title: ProPhotoRGB
Post by: lester_wareham on August 04, 2005, 04:26:37 am
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Try this. -- Pick a file with a wide color range with some colors known to be out of gamut. If the file is not already in ProPhoto then “Assign it” to ProPhoto and do a soft proof using the printer profile you plan to use and turn on Gamut Warning. Observe. Now Assign the same file to MatchColor. Much less out of gamut colors.
Yes I have tried that and what would have clipped with AdobeRGB was clipping in ProPhoto anyway (Epson 1290 Premium Photo Glossy and a bit less in heavy matt).

SO not an issue with the current printer. I guess it may be an issue for future printers.

Thanks for the links everyone, I will study these.
Title: ProPhotoRGB
Post by: Mark D Segal on August 05, 2005, 07:57:49 am
Jonathan, from my posts above - based on what I've heard at seminars and read about this matter we're on the same wave length about using proPhoto, but the thing that really intrigues me is how relatively small are the color gamuts of our printers  - seemingly ALMOST to the point that differences in gamut shape could still have some effect for some hues, but perhaps with very low probability of occurrence - oh, and by the way, next time I need expert advice on the anatomy of a weasel I'll know where to turn.
Title: ProPhotoRGB
Post by: Hermie on August 05, 2005, 03:08:04 pm
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Only working in Adobe1998 you have less room to get lost in compared to ProPhoto.

Why are you so scared to get lost Paul ;-) ? You probably didn't get lost in aRGB and you won't in ProPhoto (as long as you edit sensibly, which of course applies to aRGB too).

I also would like to add 2 comments that Bruce Fraser wrote on the Adobe forums.

Comment 1:
- adds info to DigiDog's comment "As for the idea of a wider space only being useful for very saturated colors, there’s more to it than that"
- addresses clipping

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"If you look at RGB matrix spaces (i.e., those defined by a white point, primaries, and gamma-defined tone curves) in a 3D lab plot like those offered by the ColorSync utility or Steve Upton's indispensible ColorThink, you'll see that they all reach their maximum saturation at a fairly high luminance level. The gamut narrows dramatically at lower luminances, tapering to a point at black.

Print spaces plotted the same way have a different shape, where maximum saturation is acheived at lower luminance levels. (In an RGB space, you make more saturation by adding light, on a printer you make more saturation by adding ink, so this makes sense.)

So an RGB matrix space that has a wide enough gamut at lower luminances to hold the printer gamut has to have extremely wide primaries that may not represent anything that's physically possible. Obviously, that leads to the space containing non-realizable colors. It's the trade-off you make when you want to create an RGB matrix space that contains all the realizable colors from your printer, and that's why ProPhoto is so large.

Then there's the question of clipping. It's not at all hard to capture colors that are outside Adobe RGB. Many of the dark greens and yellows that are prevalent in nature are outside Adobe RGB, and if you convert to Adobe RGB, or a smaller space, gradations of those colors get clipped to solid blobs. There's already been at least one such problem image posted on this forum. So the advantage of ProPhoto isn't about retaining all those out-of-gamut colors per se, it's about maintaining the distinctions between them, so that you can map them into printable space as gradations rather than blobs."

Comment 2 on bit depth:

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"I know of less than a handful of capture devices that claim to capture a full 16 bits, and I'm skeptical about at least half of them.

Photoshop's 16-bit implementation gives you 32,769 levels (0-32,768) and the topic as to why that's the case has been done to death here and elsewhere.

I've been using that implementation in ProPhoto RGB for about seven years now, with a variety of capture devices ranging from 10-bit to 14-bit capture. You can make any file fall apart if you push it hard enough, but 12-bit capture devices are more than capable of withstanding the rigors of ProPhoto RGB. (I'm careful not to advocate it, but I've been known to edit 8-bit files in ProPhoto without anything terrible happening....)"

Herman
Title: ProPhotoRGB
Post by: digitaldog on August 06, 2005, 01:31:34 pm
-->To comment on my question:  Yes, those silent assumptions exist, but ... “That is closely held secret by GMB. Likewise with Monaco/X-Rite. The color space assumptions in ProfileMaker differ based on the parameters used when the profiles are construed.” (by Ethan Hansen).
If anyone knows more, please post.

By the time an output profile “gets” data, it’s gone through the PCS and is in LAB. So if I’m understanding where you’re coming from, I'd say again that the output profile has no real idea what the incoming data is as far as the original RGB color space (sRGB, ProPhoto etc). The conversion takes place like this; working space (let’s say sRGB for one file, ProPhoto for another) converted to LAB by the CMM. That’s the device independent color space used by the PCS. LAB to output profile now takes place. So the output profile has no idea if the LAB data came specifically from sRGB or ProPhoto RGB. Yes, the data is different for obvious reasons and yes, with some imagery, the smaller color space CAN be somewhat beneficial. But the CMS as yet has no provisions to know this. The output profile is simply getting LAB values to work with.

The opposite is the case with device links. I’ve never seen one that works RGB to RGB but haven’t really looked or tried to build an RGB device profile since I don’t know what that would bring to the party (and Photoshop and many other ICC aware applications can’t handle Device Links). But with a device link, the advantage is you can produce a CMYK to CMYK conversion without a trip into LAB; there’s no PCS in the process. This is useful when doing CMYK to CMYK conversions because you can retain the black generation. When you do this using ICC profiles, there’s a trip into LAB, the black generation is hosed. So with device links, there’s a direct relationship between source and destination but for a specific reason.

-->Today’s printer resp. printer profiles are not prepared for the case the we come along with a heavy-loaded file in ProPhotoRGB.

I don’t see it that way. It really doesn’t matter. The printer has a fixed gamut. The original data has a fixed gamut. You want (or maybe you don’t want but I do want) all the color the capture device was capable of producing. Printer A may be able to use 80%, printer B may only be able to use 60%. That’s just the facts of life and you either have a source space that contains the colors or you don’t. This isn’t going to affect the printer; a smaller source isn’t going to allow you do reproduce any more colors (only less). So I don’t see why originally containing less colors versus more is any way a factor here.

-->The mantra "use ProPhotoRGB to avoid channel clipping“ is akin of self-fulfilling prophecy, because ACR doesn’t support any other rendering option (yet). Hence, all the burden of a perceptual de-saturation is imposed either to the operator or to the printer profile….

There’s only one rendering intent (actually one table, two intents) you can use with matrix profiles (Adobe RGB (1998), ProPhoto etc) and that’s colorimetric. If you’re asking for some kind of protectoral option, I guess that’s reasonable and I don’t know enough to say if that’s doable or useful. But the facts are, we have capture devices that can produce a very wide gamut of colors and tones we probably can’t output today and maybe never will.

-->Could the industry please kindly sort this out without involving us customers. Not everyone loves to fiddle with the Hue&Sat.-tool or the Channel Mixer to tame out-of-gamut colors.

Out of gamut colors are a fact of life and users need to decide how they wish to handle them. There is no one-size fits all conversion. That’s why we have different rendering intents, soft proofing and tools like Photoshop to attempt to produce a reproducing on a smaller gamut, lower dynamic range output device to fit our idea of what the image should look like.

We’ve never been able to reproduce the gamut and range of a transparency on print but that didn’t stop people from making beautiful representations of the film for years.

-->“Devices such as digital cameras and printers perform embedded (typically proprietary) perceptual renderings to and from standard color encodings like sRGB.

I’m not sure what that brings to the discussion. I suggest you read the white paper there (which I co-authored) which discusses the processes of in camera rendering and encoding.

http://www.color.org/ICC_whi....ics.pdf (http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf)
Title: ProPhotoRGB
Post by: PeterLange on August 07, 2005, 07:49:18 am
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Any “best practice” how to proceed?
Yes, use Photoshop's softproofing to see what the heck the image will look like when printed, pick the best rendering intent for the image and under softproofing, adjust the image to achieve the results you want.
Jeff,

Two questions please; one technical and one workflow-related.

The Color Range tool offers an option to select “Out Of Gamut” colors.  Which target profile does it refer to?  It seems that the selection differs considerably from the SoftProof / out-of-gamut marks.


After you’ve processed a file through Camera Raw (ProPhotoRGB, 16 bit), do you instantly enable the SoftProof to the printer/media profile, or is there an editing step in-between based on “normal” presentation on screen?

Peter

--
Title: ProPhotoRGB
Post by: Mark D Segal on August 07, 2005, 07:52:14 pm
pom, of course you're joking.........no way I would let these arcane esoterics deprive me of the benefits of digital.

Peter - fine, the same thing with added detail, but so what? The bottom line is that anyone claiming a significant downside to working in Prophoto color space needs to demonstrate in normal photographic prints that rendering intents have a differentially negative impact on posterization as you move from smaller to larger embedded or working color spaces relative to the (fixed size) output color space. It is not clear in principle and where is the practical real-life evidence?
Title: ProPhotoRGB
Post by: Ray on August 09, 2005, 09:54:18 pm
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I’m not sure what you mean “the sRGB image required less desaturation”.
The sat slider of the PS hue/sat tool required less adjustment to remove all of the grayed-out areas (-68 for sRGB as opposed to -71 for the ARGB image and -62 for PP), all in relation to the Bill Atkinson Prem Gloss profile.
Title: ProPhotoRGB
Post by: digitaldog on August 10, 2005, 12:20:51 pm
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When you convert (one step), that’s EXACTLY what you get.
Andrew, the softproofing you describe in your last post above is what I have been doing but the phrase I quoted confuses me. I have the softproof set-up the way you say, and to activate it I click "CTRL Y" (Windows XP) which I understand doesn't change anything in the image file - it "simply" renders a monitor image simulating what the printed output will look like - and it does so pretty well. When I click CTRL Y again the simulation disappears. Is this what you mean in the above quote from your post, or do you mean that once I click "PRINT" Photoshop remaps the file data to the output profile for printing (but doesn't retain the remapped data thereafter) or do you mean something else?
No, I was referring to the Gamut Warning option in the same menu that places an ugly gray (by default) mask over out of gamut colors. That’s not the same as using the Soft Proof with an output profile.
Title: ProPhotoRGB
Post by: Mark D Segal on August 11, 2005, 08:18:11 am
Yes Ray, I think we have all been through that stage!!!

I appreciate your observations on predictability of shadow detail using Gamut Warning vs Soft Proof when switching rendering intent. I haven't made this exact comparison, so it will be interesting to see Andrew's comment on this.
Title: ProPhotoRGB
Post by: Ray on August 14, 2005, 10:04:52 am
Does anyone use the 'saturation' intent for photos, as opposed to graphics? I find that with some images, perceptual or relcol produces a significant dulling effect with proof colors (on screen) but not with 'saturation'.
Title: ProPhotoRGB
Post by: Ray on August 17, 2005, 09:35:29 am
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No, that's not the right figure.

2 to the power of 48 is:

281 474 976 710 656
Okay! So it's 281 British billion. That's an even more unrealistic figure. You'd need a Supercomputer and a lot more than Photoshop to handle an image containing all those colors. Does a few billion make any difference in such circumstances, apart from slowing everything to a crawl.
Title: ProPhotoRGB
Post by: Ray on August 17, 2005, 10:36:29 am
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48 * 300 000 * 300 000 = 4 320 000 000 000 bits = 540 000 000 000 bytes.
Which is approximately 135x the maximum size the TIFF file format can support.  :D
Title: ProPhotoRGB
Post by: lester_wareham on August 03, 2005, 02:49:43 pm
Is anyone out there using ProPhotoRGB instead of AdobeRGB?

I notice I get a lot less trouble with clipped coloured  highlights in ACR using the wider ProPhoto.

What's the pro's and con's?
Title: ProPhotoRGB
Post by: paulbk on August 04, 2005, 04:05:23 am
Maybe he’s photographing canaries and doesn’t mind huge steps in color tone. All you get is 256 tones REGARDLESS of the color space (sRGB, Adobe1998, or ProPhoto). Stretch 256 tones over a large color gamut and banding could be troublesome. Depends on the photo. Further, your eye is more sensitive to color contrast than to absolute color. Your eyes adjust just fine to tungsten light even though the full spectrum colors are way off. A smooth transition in a sunset spectrum or the iridescence in a feather is more pleasing than a blotchy long jump to the next shade.

The academic argument for ProPhoto is far from a decided issue. In the end, it’s all in the print.
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 08:52:50 am
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These values are all out-of-gamut, indicated by the exclamation mark, but in relation to the SWOP standard, I assume. But there's a question here that perhaps someone would like to answer.
If you load a soft proof of your output device and then in the Info palette use Proof Colors, you can see the effect on that device (not SWOP).

As for the idea of a wider space only being useful for very saturated colors, there’s more to it than that. Due to the simple shape of these synthetic working spaces, many, especially those that are not real large don’t produce a good fit for the output device gamut, especially saturated colors in the output space that are very dark. If you look at good 3D maps, you see this. So in order to fit these colors, the primaries are (like ProPhoto RGB) stretched out to accommodate these areas. That’s one reason when you look at even a 2D plot of ProPhoto you see the Blue falling outside the CIE chromaticity diagram (it’s by design of course).
Title: ProPhotoRGB
Post by: paulbk on August 05, 2005, 02:30:43 pm
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and funny enough the same statement (although to a lessor degree) is true for Adobe RGB.

Hermi, You are right! That's exactly my point. Only working in Adobe1998 you have less room to get lost in compared to ProPhoto.
Title: ProPhotoRGB
Post by: digitaldog on August 06, 2005, 02:54:41 pm
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It seems there is no downside to this.
Offered without comment, since I'm not qualified to comment, but an article discussing potential downsides:

ProPhoto or ConPhoto? (http://www.jeremydaalder.com/singleArticle.php?articleID=6)

Giles
I actually went to read up on this article and without going to far, found this:

-->All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!

That’s not really so. This is a fundamental misunderstanding of what a color space is. So I’ll do a quick copy and paste from some text I wrote:

What is a color space? Think of it this way: suppose I supply a recipe for chocolate chip cookies but do not provide the unit for each ingredient in the recipe. The recipe provides each ingredient followed by a number. Without units you can’t make the cookies. The numbers alone are not enough information to describe how the cookies that will be produced. Likewise, R78/G103/B23  or C23/M98/M123/K6 is not enough information to reproduce that color.

Going back to the chocolate chip cookie analogy, suppose a color model is a cookie recipe with only three ingredients. I give you this recipe, which simply calls for 1-flour, 8-butter and 2-chocolate chips. You don’t have enough information to make the cookies. However if I provide you the recipe with a specific scale—1 cup of flour, 8 tablespoons of butter, and 2 cups of chocolate chips—I’ve provided the necessary information, the scale, to make a dozen chocolate chip cookies. I can give you the cookie recipe in the metric scale such as liters and grams and you can still makes the same cookies even though the numbers are different. A color space is a color model that has a known reference and scale, in this case primaries (the ingredients) and scale (specific quantities of these ingredients).

Suppose I specify a color as R10/G130/B50 and specify a color reference by saying the color space is Adobe RGB (1998), which defines the scale of the RGB primaries; the color coordinates of this color space. The R10/G130/B50 set of numbers can now reproduce a color by anyone with the proper tools since the reference and scale have been defined. Different RGB color spaces use a different scale of red, green, and blue primaries. Adobe RGB (1998) and sRGB  are different color spaces, however both are based on the RGB color model using RGB primaries. Although each color space uses the same three primary ingredients (R, G, and , the specific colorimetric scale of each color space is different. The maximum of red, green, and blue are more saturated in the Adobe RGB (1998) color space than the sRGB color space. Even though R0/G255/B0 is the greenest green ingredient in both Adobe RGB (1998) and sRGB, knowing that the scale is different in both color spaces explains why this green value is more saturated in Adobe RGB (1998). This also illustrates how R0/G255/B0 alone can’t tell us what green.

An ICC profile simply defines this scale and gives the numbers a meaning allowing us to reproduce the color using something far more concrete than using the English word "Green" or a set of numbers which alone is far too ambiguous to produce a specific color appearance.

-----

So going back to “That is, a bigger colour space does not mean there are more colours in total” the issue here is saturation of the primary colors (RGB in this case). Yes, R255 in sRGB and ProPhoto RGB share the same number but most certainly not the same scale.
Title: ProPhotoRGB
Post by: PeterLange on August 07, 2005, 07:41:38 am
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As far as I have been able to parse it, this whole discussion about whether or not it is useful to work in ProPhoto color space so far boils down to two propositions: (a) if Prophoto includes - but ARGB98 excludes - values that current and future generations of printers can reproduce, we should retain those values because they will improve printed image quality; ( as long as we work with 16 bit data, there is very little risk that Photoshop's shakedown of out of (printer) gamut colors will produce any noticeable banding.
Mark,

Referring to point (b.), there are two different mechanisms involved:

Posterization is supported by large spaces with high gamma at low bit depth.  For me, it’s a non-issue with ProPhotoRGB at 16-12 bit/ch.

Posterization is a real-world threat (IMO), when you convert a large space such as ProPhotoRGB (including rich colors) to a printer/media profile.  All the color space volume in-between the source and the target space is collapsed on surface of the latter one.  It’s often easily obvious from the print that exactly those out-of-gamut colors why we like to use a large working space have lost details.

Therefore it seems to be required to edit & de-saturate said out-of-colors by hand “into” the printer/media space.

Peter

--
Title: ProPhotoRGB
Post by: Ray on August 08, 2005, 12:32:02 am
The last time I tried to do some comparison print tests between perceptual and relative colorimetric with an image with out of gamut colors, I couldn't see any differences. The explanataion at the time was (about a couple of years ago) that unless the paper/printer profile you are using addressed such issues when it was built, then you won't see any difference.

My general feeling is, there's a lot of stuff that's supposed to have an effect in theory, but in practice the effect can be either insignificant or completely dwarfed by other greater influences.

That's why it's necessary to test things for yourself. Don't take anything on trust  :) .
Title: ProPhotoRGB
Post by: digitaldog on August 09, 2005, 09:40:00 pm
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Brighter (more saturated, or perhaps more intense is the right word) on screen immediately after assigning the 3 profiles, but also after applying proof setup/simulater paper white etc and reducing gamut for all 3. The sRGB and ARGB rainbows are dowdy by comparison.

If the numbers are the same, it would seem the reason why the ProPhoto image did not require the same degree of desaturation as the ARGB image (to bring them both within gamut) is a result of the Premium Glossy paper's capacity to handle at least some of the greater saturation of ProPhoto. Does that make sense?

The surprise is, the sRGB image required less desaturation to bring it within gamut than did ARGB. It would make more sense if this was the other way round.
Assigning the profiles would of course change the color appearance from prior to the assignment. The soft proof would look different as well. When you Assign a profile, you change the meaning of the numbers so Photoshop updates the preview based on those new definitions (even though the numbers are the same).

I’m not sure what you mean “the sRGB image required less desaturation”.
Title: ProPhotoRGB
Post by: Mark D Segal on August 10, 2005, 12:26:47 pm
No - you could NOT have been referring to the Gamut Warning in that sentence, or you put that sentence in the wrong paragraph, or I don't understand. Please re-read your paragraph in which you have that sentence I quoted about converting in one step, then please re-read my question and let me know if you would like to revise that answer.
Title: ProPhotoRGB
Post by: Ray on August 10, 2005, 11:42:22 pm
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It is true that you do not see everything that is going on until it is done, but that hardly matters;

It sure does if you want to save ink and paper. I've been through the stage of wasting lots of that.

I'll give you an example from the last time I tried comparing 'perceptual' and 'relcol'. I was using Epson's profiles for Premium Gloss and Photopaper on the 1290. I knew premium gloss claimed to have a wider gamut than photopaper, and the gamut warning showed it in proof setup. The images on screen looked very similar for both profiles, but the gamut warning showed heaps of gray blotches in the shadows with proof setup set to the Photopaper profile. With the Prem Gloss profile, there was just the barest hint of gray specks. This out-of-gamut warning was confined to the shadows and I was interested to see how the different rendering intents of preceptual and relcol would handle this.

I could see no significant differences in the two rendering intents, but there sure was a big difference in shadow detail in the two prints.

Premium Gloss produced shadows with good detail as seen with proof colors on screen. The same image printed on Photopaper showed blocked up shadows. The Photopaper print was a waste of ink and paper, yet there was nothing I could see using proof setup, apart from the gamut warning, that would indicate I would possibly get blocked shadows.

I'm simply asking Andrew, in this situation I've described, how could I forsee that the shadows on Photopaper might be blocked up, without using the gamut warning. What's the alternative technique?
Title: ProPhotoRGB
Post by: digitaldog on August 14, 2005, 10:19:41 am
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Does anyone use the 'saturation' intent for photos, as opposed to graphics? I find that with some images, perceptual or relcol produces a significant dulling effect with proof colors (on screen) but not with 'saturation'.
Depending on the profile (how it’s built, the package that built it), it can work well. So I would not dismiss it outright.
Title: ProPhotoRGB
Post by: Mark D Segal on August 17, 2005, 12:38:15 pm
Interesting discussion. I shall now stick my head out - by sticking my two-cents-worth in. I have no doubt I shall be summarily corrected if I am wrong. My understanding is that a color space is not measured in the same way a digital image is measured. A color space is measured by its CIExy co-ordinates. It is device independent and has nothing to do with pixels and number of discrete HSB values in a digital image file.

Turning to capture devices, the maximum number of individual HSB values any pixel represented by the photosites in the sensor can capture depends on pixel bit depth. For example, a Canon 1Ds has a sensor of bit depth = 12, hence each pixel can theoretically contain any one of 68.7 billion hues [(2^12 per channel)^3 channels]. But since there can be only one HSB value per pixel, the maximum number of different HSB values the image will contain depends approximately on the sensor's pixel dimensions: e.g. on the Canon 1Ds 11.1 MP.

See Blatner/Fraser Real World Photoshop page 171, where it is explained aproximately as follows: if image capture is in 8 bit mode there are 256 possible values per channel, regardless of the working space. The larger the color space the more these values get stretched over that space and the higher the risk of banding from image adjustments that reduce levels. A 16 bit image virtually eliminates that danger because there are exponentially more color values, hence exponentially less stretching of those color values over the color space whatever the CIExy contours of the color space. They advise selecting the working space that is an appropriate balance between gamut size and editing headroom, noting that with 16 bit images there is no issue.

I conclude from this little assembly of information that I can happily work in ProPhoto color space with my 16 bit files, but if I worked with 8 bit images that need major editing, I could be safer using something smaller such as ARGB98.
Title: ProPhotoRGB
Post by: digitaldog on August 17, 2005, 09:23:11 am
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A bigger space DOES mean more colors.
With "A bigger space DOES mean more colors.", I meant more colors in the sense of a larger volume/scale in LAB (more saturation etc.).
I’d say so, most certainly!
Title: ProPhotoRGB
Post by: Hermie on August 03, 2005, 03:43:57 pm
Take a look on the Adobe forums e.g.:

http://www.adobeforums.com/cgi-bin....bb5f89c (http://www.adobeforums.com/cgi-bin/webx?128@521.6gG0eygTNGy.48@.3bb5f89c)

http://www.adobeforums.com/cgi-bin....bbabc37 (http://www.adobeforums.com/cgi-bin/webx?128@521.6gG0eygTNGy.52@.3bbabc37)

See also Mike Chaney (Qimage) and Andrew Rodney (Digital Dog):

http://forums.dpreview.com/forums....3979411 (http://forums.dpreview.com/forums/read.asp?forum=1003&message=13979411)
Title: ProPhotoRGB
Post by: Hermie on August 04, 2005, 02:43:45 am
Andrew Rodney's reply is key here:

"Yup, if in ACR I see clipping in say Adobe RGB (1998), I'll go directly to ProPhoto."

Herman
Title: ProPhotoRGB
Post by: Jonathan Wienke on August 05, 2005, 02:34:55 am
The bottom line is that if editing sensibly in 16-bit mode (not doing ridiculous saturation boosts, etc) there is no real disadvantage to ProPhoto. You're pretty much guaranteed to be able to use 100% of the gamut of any output device, something which is not true for any other color space in common use.

And 30,000 is the number of hairs on the average newborn weasel.  :angry:
Title: ProPhotoRGB
Post by: paulbk on August 06, 2005, 08:59:15 am
Ray.... "Is this what you're getting at, Paul"

Yes.. but you changed my test some what. I made a 10x10 pixel file of R=255 in ProPhoto. Another of R=254 in ProPhoto, and another of R=253 in ProPhoto. I then did a print to file using my Epson 4000 HahnRag printer/paper profile. The files are the same.

You can also do a convert to profile (ProPhoto > HahnRag) for each and you will find the Lab values for all three patches are the same. I.e., the print is the same even though in ProPhot they are different files. It looks like ProPhoto sat. red doesn't come into HahnRag gamut until about 170. And yes, I understand the printer receives some mix of ink values in an attempt to reach ProPhoto sat. red.

My point is fiddling with out gamut colors (printer/paper gamut) is a stumbling art at best. Occasionally a "fine art" in the right hands. Jeff and Rodney live and breathe this stuff 24/7. They know how to work within the limitations of the technology. Those who pooh pooh the J. Daalder reasoning haven't read it or don't understand it. By the way, Mac Holbert says the same thing. He recommends a tight color space with respect to your print space. Holbart used ColorMatch on Ep2200.
Title: ProPhotoRGB
Post by: Hermie on August 07, 2005, 11:29:45 am
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Referring to point (b.), there are two different mechanisms involved:

Posterization is supported by large spaces with high gamma at low bit depth.  For me, it’s a non-issue with ProPhotoRGB at 16-12 bit/ch.

Posterization is a real-world threat (IMO), when you convert a large space such as ProPhotoRGB (including rich colors) to a printer/media profile.  All the color space volume in-between the source and the target space is collapsed on surface of the latter one.

Peter, except for the camera colors that ProPhoto RGB retains, aRGB clips, and can be printed, what's the practical difference between:

Workflow A: Working space is aRGB.
- All out-of-gamut camera colors are clipped along the edge of aRGB
- When converting to a printer profile, all out-of-gamut aRGB colors (this means INCLUDING clipped camera colors) are clipped/compressed (depending on rendering intent) along the edge of the output space.

Workflow B: Working space is ProPhoto.
- There are no out-of gamut camera colors.
- When converting to a printer profile, all out-of-gamut ProPhoto RGB colors are clipped/compressed (depending on rendering intent) along the edge of the output space.

In workflow A camera colors are clipped in 2 steps, in workflow B in one step.

Herman
Title: ProPhotoRGB
Post by: digitaldog on August 09, 2005, 12:55:12 pm
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Andrew, fine. But what is the relevance of this information to the issue of whether there is downside risk (in terms of visible degradation of print quality) when using ProPhoto rather than ARGB98 as one's default colour space?
Personally I don’t see any real downside other than you’re dealing with one space that could contain a lot more colors you can’t see on screen compared to the other. However, you can also see how the mapping from a very large space compared to a smaller space is being affected by your output profile (since ultimately we need to print the thing).
Title: ProPhotoRGB
Post by: digitaldog on August 10, 2005, 10:16:38 am
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So now you tell me  ! What is Adobe doing providing a useless gamut warning? I've been relying on that gamut warning to fine tune my images before printing.

Are you saying I should just ignore this gamut warning, switch it off and make the colors as bright and saturated as I like?
Yes, ignore it. It’s totally legacy and yes, it’s totally useless. They also supply the “Classic” CMYK engine which expect for old farts in Prepress, is useless. If they pulled it (which they would love to do), a small vocal group would go nuts.

Look at this warning. It places an ugly gray (by default) mask over your image, you can’t see a thing. Then you’re supposed to manually desaturate the image to make it go away, indicating in the crudest fashion that those colors are now “in gamut”.

Or you can setup a soft proof with your output profile and rendering intent. The profile has far more robust control over gamut mapping (compression or clipping) and it shows you EXACTLY the mapping and gamut reduction without an ugly, useless overlay. When you convert (one step), that’s EXACTLY what you get.

You’d rather use a sponge tool and do this manually, slower and far less accurctly? The gamut warning overlay is about as useful as retouching blemishes with the pencil tool!

Use the soft proofing functionality in Photoshop!
Title: ProPhotoRGB
Post by: Mark D Segal on August 10, 2005, 10:17:34 pm
Ray, the options you quote from Andrew is actually his clearest post in the whole thread. I think he is right, but I see where you are coming from.

What I think it boils down to is that Photoshop will do a better job of dealing with out-of-gamut colours than you or I can. If optimal results could be achieved simply by tweaking the saturation slider, it is unlikely Adobe's engineers would have put the time and effort they have into the conversion process from working space to output profile. One needs to presume that Photoshop's mathematics have been designed to handle all this under the hood much more intelligently than you or I can achieve with one simple tool.

It is true that you do not see everything that is going on until it is done, but that hardly matters; if you don't like a soft-proofed image you still have two options: (i) further tweak any image adjustment tool you like with the soft proofing active (in fact, I make luminosity and color balance adjustments with soft-proofing active), and/or (ii) change the rendering intent to see whether for a particular image a departure from your usual rendering intent works better. With good soft-proofing you come awefully close to WYSIWYG (provided your monitor is properly calibrated and profiled), and after all, isn't that the objective?
Title: ProPhotoRGB
Post by: Mark D Segal on August 14, 2005, 10:23:33 am
Interesting idea, may be worth giving it a whirl, despite what Blatner/Fraser say about it on page 142 of Real World Photoshop CS:

"The saturation intent maps fully-saturated colors in the source to fully-saturated colors in the target without concerning itself with hue or lightness. It's good for pie charts and such, where you just want vivid colors, but not much else."
Title: ProPhotoRGB
Post by: Ray on August 17, 2005, 09:59:28 am
Quote
Quote
A bigger space DOES mean more colors.
With "A bigger space DOES mean more colors.", I meant more colors in the sense of a larger volume/scale in LAB (more saturation etc.).
I’d say so, most certainly!
I just can't understand that statement. I have an sRGB 24 bit 50MB image that contains every combination of the 255 levels of red, green and blue; ie 16.7 million colours, each pixel representing a different colour. (Give or take a few hundred or thousand, Jani  :D ).

I convert the image to the bigger ProPhoto color space. I've still got 16.7 million colors. If I were to get more, the file size would have to increase. I've never noticed that happen, have you?

If I say the colors have changed in character; that some of them are more saturated than they were in the sRGB space, then that is a different statement to saying I have more colors. Let's try to be logical here. More colors does not mean more color, if English is your first language. If you think it does, then thats the source of the confusion. By 'more colors', I mean 'a greater number of discrete shades of color'.
Title: ProPhotoRGB
Post by: Ray on August 17, 2005, 10:26:29 am
Quote
Now if you want to debate that the max red in one color space which is more saturated than another isn’t really “more colors”, OK.
Well, it needs clarifying doesn't it. I get the impression some folks reading this might think a wider range of colors between extremes of saturation translates to a greater number of colors.

Perhaps you mean, the bigger the color space, the wider the gap between a given number of colors and the greater the possibibility of the eye being able to distinguish between the different shades. I would think that the difference amongst 50 shades of red evenly spaced between 1,0,0 and 255,0,0 in Prophoto would be slightly more noticeable than 50 shades of evenly spaced red in sRGB.
Title: ProPhotoRGB
Post by: digitaldog on August 03, 2005, 04:53:12 pm
Quote
Is anyone out there using ProPhotoRGB instead of AdobeRGB?

I notice I get a lot less trouble with clipped coloured  highlights in ACR using the wider ProPhoto.

What's the pro's and con's?
Yup, if in ACR I see clipping in say Adobe RGB (1998), I’ll go directly to ProPhoto.
Title: ProPhotoRGB
Post by: paulbk on August 04, 2005, 02:40:50 am
Read the link white paper. The triangle you point to is discussed, thus:

"What on earth does this have to do with ProPhoto? Well, I'm glad you asked. It has to do with the gamuts of current output devices. They're not that big. Certainly, in volume terms, they are ALL pretty much smaller than even AdobeRGB. This includes - Lightjets, Lamdas (see Figure 5), Thetas, Pegasusses (Pegasi?), Canon, HP and Epson inkjets (see Figure 4), Dye Subs, and You-Name-Its. Not one of them has a gamut larger than AdobeRGB in total. However, some (many) do have gamuts that do not completely overlap AdobeRGB. In some case, as much as 5 to 10% of their gamut may be out of Adobe RGB. Typically, it is saturated yellows that are the culprits (sometimes very saturated cyans and magentas, too, although this is less common)."

"So, unless you are shooting canaries (or more realistically, very unusually intense sunsets - see Figure 6), almost all of the tones you can print or are likely to be able to print in the short to mid term future, are nicely contained within AdobeRGB. So working in Adobe RGB rather than ProPhoto RGB makes more sense (you'll see why in a moment). Of course, for those images that DO contain out of Adobe RGB gamut colours that ARE printable, you probably would choose ProPhoto. But you'd be doing so for a sensible, distinct reason."
Title: ProPhotoRGB
Post by: PeterLange on August 06, 2005, 01:10:29 pm
Quote
Quote
Quote
Quote
First, with rendering intents to output spaces, you have to decide if you’ll clip the colors or compress them. ...
Just a friendly question:
 
Are there any printer profiles
which support Perceptual rendering in way
which assumes that the source space was ProPhotoRGB?

Peter

--
No. Output profiles don’t have any idea when built what the source color space will be.
 

Doesn’t the profiling software implement the Perceptual intent
and its non-linear transforms
based on a on a silent assumption about the source color range?

Peter

---

To comment on my question:  Yes, those silent assumptions exist, but ... “That is closely held secret by GMB. Likewise with Monaco/X-Rite. The color space assumptions in ProfileMaker differ based on the parameters used when the profiles are construed.” (by Ethan Hansen).
If anyone knows more, please post.
----


My claim is straightforward and quite fair:  Today’s printer resp. printer profiles are not prepared for the case the we come along with a heavy-loaded file in ProPhotoRGB.

If you really have those colorful flowers
– which are well preserved in a ProPhotoRGB container -
many colors will posterize at the border of the printer/media-space
independent whether you choose RelCol or Perceptual.
Just try it.

The mantra "use ProPhotoRGB to avoid channel clipping“ is akin of self-fulfilling prophecy, because ACR doesn’t support any other rendering option (yet). Hence, all the burden of a perceptual de-saturation is imposed either to the operator or to the printer profile….

Could the industry please kindly sort this out without involving us customers. Not everyone loves to fiddle with the Hue&Sat.-tool or the Channel Mixer to tame out-of-gamut colors.

Peter
---


Here’s an interesting reference (ICC White Paper #2 from www.color.org):

“Devices such as digital cameras and printers perform embedded (typically proprietary) perceptual renderings to and from standard color encodings like sRGB.

Finally, a color management system (CMS) may offer color rendering or re-rendering capabilities beyond that built into any source and destination profiles.”

---
Title: ProPhotoRGB
Post by: Mark D Segal on August 07, 2005, 09:21:52 am
Peter, I don't think that is correct. Firstly we are not converting a color space to a printer profile. As I mentioned above the printer profile measures and corrects differences between the file data and how the printer reproduces that data.

The color space the printer can reproduce is smaller and most importantly shaped differently than say the prophoto or ARGB98 working color space in Photoshop. The rendering intent selected in Photoshop determines how those out of gamut colors are dealt with, and consequently the impact on the appearance of the soft-proof or the print.

I would be interested to see photographs (not gamut diagrams) made from 16 bit files where there is more banding or posterization as a result of the operation of the same rendering intent in ProPhoto versus ARGB98. Personally I have NEVER YET had to rescue an image from banding or posterization by hand because I am working in ProPhoto.
Title: ProPhotoRGB
Post by: Ray on August 05, 2005, 03:51:56 am
But seriously, just how many discrete colors are there in the average 24 bit 33MB 1Ds image? Maybe not 30,000, although I bet some images would have no more than that. 100,000 perhaps? Certainly less than 1 million.
Title: ProPhotoRGB
Post by: Mark D Segal on August 09, 2005, 12:49:08 pm
Andrew, fine. But what is the relevance of this information to the issue of whether there is downside risk (in terms of visible degradation of print quality) when using ProPhoto rather than ARGB98 as one's default colour space?
Title: ProPhotoRGB
Post by: Mark D Segal on August 10, 2005, 11:27:46 am
Quote
When you convert (one step), that’s EXACTLY what you get.
Andrew, the softproofing you describe in your last post above is what I have been doing but the phrase I quoted confuses me. I have the softproof set-up the way you say, and to activate it I click "CTRL Y" (Windows XP) which I understand doesn't change anything in the image file - it "simply" renders a monitor image simulating what the printed output will look like - and it does so pretty well. When I click CTRL Y again the simulation disappears. Is this what you mean in the above quote from your post, or do you mean that once I click "PRINT" Photoshop remaps the file data to the output profile for printing (but doesn't retain the remapped data thereafter) or do you mean something else?
Title: ProPhotoRGB
Post by: Ray on August 10, 2005, 08:43:39 pm
Quote
There are two options for viewing out of gamut colors under the View menu. One is to setup a soft proof using the output profile, rendering intent and options like Simulate paper/ink. This IS the way to be evaluating the soft proof/out of gamut colors.

The second, older and quite useless way is to pick “Gamut Warning” which places a gray (by default) mask over out of gamut colors based on what you’ve set in Proof Setup. The idea is to desaturate those areas so they fall into output gamut. This is a old, useless, time consuming and not very accurate way to be handling this process.
Well, you guys have got me completely confused. I see only one way of knowing which colors are out of gamut and that's by ticking the gamut warning under 'proof colors' which places a gray mask over the saturated colors.

Perhaps there's something very obvious that has escaped me, but if I don't see the gray mask, how do I know the colors might be too saturated for the paper/printer?

I understand the point that Adobe's gamut warning might be hoplessly inaccurate and that it's better to let the rendering intent (perceptual or whatever) remap the colors so one can be sure one is getting the maximum saturation of a particular color on the paper, if that was the idea when editing, ie. maximum impact of that yellow flower without losing detail.

But 'not knowing' that the colors are going to be remapped, that some of the hues are going to be changed in subtle ways and possibly some of the shadows blocked up because of dark, out-of-gamut shades, seems to me less than ideal.

What's the more precise alternative to the gamut warning, Andrew? This is not clear in your above statements.
Title: ProPhotoRGB
Post by: digitaldog on August 14, 2005, 10:40:11 am
We’re in agreement. On page 35 of my book:

The saturation rendering intent was at one time recommended for solid graphics like logos or pie charts (sometimes referred to as business graphics) and the gamut mapping is weighted to produce the most vivid saturated colors (hence the name). For this reason, using this intent on images can produce less than desirable results. However, depending on the profile and how it was built, the saturation intent might be fine for some images so don’t dismiss it outright. In most cases, this intent really is going to be best used for files that don’t contain images and for use on business graphics and similar types of imagery.  Like the perceptual rendering intent, there are no specifications for how this intent should be applied, so various profiles from different manufacturers will produce differing results.
Title: ProPhotoRGB
Post by: digitaldog on August 17, 2005, 09:51:03 am
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Quote
No, that's not the right figure.

2 to the power of 48 is:

281 474 976 710 656
Okay! So it's 281 British billion. That's an even more unrealistic figure. You'd need a Supercomputer and a lot more than Photoshop to handle an image containing all those colors. Does a few billion make any difference in such circumstances, apart from slowing everything to a crawl.
NO image could contain that color. Even if it could, we could see a tiny fraction of those colors (we can’t even see anything close to 16 million color simultaneously). This is all math being used to define a possible but unfortunately impossible human experience. Don’t forget, there’s math that says a bumblebee can’t fly.
Title: ProPhotoRGB
Post by: jani on August 17, 2005, 10:26:40 am
Quote
NO image could contain that color. Even if it could, we could see a tiny fraction of those colors (we can’t even see anything close to 16 million color simultaneously). This is all math being used to define a possible but unfortunately impossible human experience.
An image can contain an infinite number of colors (unless you mean to imply that wavelengths of light exist only in a finite, discrete set), but there are limits to what you can capture.

A pixel can only have one RGB value, and the limit of discrete colors in a pixel-based image therefore depends on the number of uniquely colored pixels in it.

To create an image with 281 474 976 710 656 different colors, you only need to create an image with as many pixels, all with different RGB values.

As for Ray's point about supercomputers and whatnot, the fact that we deal with RGB values per pixel indicates that an 48-bit color image's uncompressed size in memory should be:

48 bits * width in pixels * height in pixels

E.g., a 300 000 * 300 000 pixel image (Photoshop CS's maximum, right?) could be:

48 * 300 000 * 300 000 = 4 320 000 000 000 bits = 540 000 000 000 bytes.

Plus overhead.

Quote
Don’t forget, there’s math that says a bumblebee can’t fly.
Really? Please show and tell. As far as I know, this is only a popular urban legend, of the kind that is told to ridicule engineers/mathematicians/scientists. There is another, apocryphal story explaining how this misunderstanding could have spread, and it's told here:

http://www.ilr.tu-berlin.de/WKA/technik/bumblebee.html (http://www.ilr.tu-berlin.de/WKA/technik/bumblebee.html)
Title: ProPhotoRGB
Post by: Jonathan Wienke on August 03, 2005, 08:10:19 pm
The only con to ProPhoto is a slightly greater chance of posterization or banding if editing in 8-bit mode. But if you use 16-bit mode (which you should be doing anyway) this is irrelevant and there is no real downside to ProPhoto.
Title: ProPhotoRGB
Post by: digitaldog on August 04, 2005, 09:16:59 am
Quote
Maybe he’s photographing canaries and doesn’t mind huge steps in color tone. All you get is 256 tones REGARDLESS of the color space (sRGB, Adobe1998, or ProPhoto). Stretch 256 tones over a large color gamut and banding could be troublesome.
No, I bring the RAW into Photoshop in high bit (more than 8-bits per color). Photoshop calls all files with more than 8-bits per color “16-bit” (it’s actually 15 bits).
Title: ProPhotoRGB
Post by: lester_wareham on August 04, 2005, 05:09:45 pm
Quote
"So, unless you are shooting canaries (or more realistically, very unusually intense sunsets -..."
The tones I have had clipped in AdobeRGB were yellows and blues in flowers. One way around this is to reduce saturation or 'brightness' in ACR, not that nice in terms of over all image.

However some clipping might be acceptable, and as pointed out these will get clipped at output or desaturated by perceptual rendering it seems.
Title: ProPhotoRGB
Post by: Hermie on August 05, 2005, 05:38:35 pm
Quote
Why should any one edit using colors they can not print, today?
It's the "round peg in a square hole" metaphor that Andrew posted or as Bruce wrote "It's the trade-off you make when you want to create an RGB matrix space that contains all the realizable colors from your printer".

We edit using colors that we cannot print all the time when we work in aRGB or even sRGB.

Andrew, do you have any thoughts on this one:

Quote
By the way, does anyone of you use

- basICColor display profiles (gamut-compressed profiles, which reasonably simulate colors outside the monitor gamut) or
- Photoshop's "Desaturate Monitor Colors" control

in relation to ProPhoto workflow?

Herman
Title: ProPhotoRGB
Post by: digitaldog on August 06, 2005, 07:12:25 pm
Quote
Yes. As I wrote, R255 in sRGB and Adobe RGB (1998) share the same numbers. But R255 in Adobe RGB is much more saturated. If you look at the gamut plot of both in the CIE chromaticity diagram you’re seeing the two within the context of all human vision. The larger plot holds more visible colors.
Title: ProPhotoRGB
Post by: Ray on August 06, 2005, 11:22:34 pm
Quote
As far as I have been able to parse it, this whole discussion about whether or not it is useful to work in ProPhoto color space so far boils down to two propositions: (a) if Prophoto includes - but ARGB98 excludes - values that current and future generations of printers can reproduce, we should retain those values because they will improve printed image quality; ( as long as we work with 16 bit data, there is very little risk that Photoshop's shakedown of out of (printer) gamut colors will produce any noticeable banding.
Mark,
Understood! But Paul's point about the values being retained in any case if you are in the habit of keeping your RAW files (and who isn't?), has a certain validity. The argument, already made earlier, that you might not want to rework an image because you've spent a lot of time editing it, also has a certain validity, but it's not clear to me just how valid this point is.

If your monitor cannot even display the full gamut of ARGB, then how valid is any current editing in respect of an even wider gamut that you might be able to use in say 10 years' time. You are going to want to re-edit that image using a future monitor that can display the full gamut of ProPhoto.

If I'm in a situation where I'm revisiting 10 year old images with a view to reprinting them using a monitor that can display the full gamut of ProPhoto and a printer with the same capability, then I think it might be better to go to the original RAW image and reconvert it using the latest version of ACR which will almost certainly be a better converter with more options and a better capability of extracting detail and color.

So for me, the more immediate concern is, what colors and shades can we print from ProPhoto that we cannot print from ARGB, on the latest printers such as the Epson 4800, and on what papers?

Not that I'm arguing against the use of ProPhoto. If there's no downside of any practical significance, then one might as well convert into ProPhoto. It's at least another copy of the image that would certainly be more useful than an ARGB copy for future purposes if you were to lose the original RAW.

No point in needlessly depriving oneself of possibilities.  :D
Title: ProPhotoRGB
Post by: Mark D Segal on August 11, 2005, 10:00:46 am
Thanks Andrew - much better - you've provided some substantive food for thought about the conditions under which these comparisons should be made for them to be reliable. That is important. Only Ray knows how he did his comparisons, so up to him to clarify.
Title: ProPhotoRGB
Post by: Ray on August 14, 2005, 10:56:43 am
Some time ago I visited a friend I hadn't seen for some time, a French lady who has taken up painting (perhaps in preparation for her retirement). She lives in a big house with a huge living room that is adorned with very precise copies of the French imressionists, as well as Van Gogh works. (It's quite legal to copy art works as long as you don't pass them off as originals.)

Of course I photographed them all with my D60 and promised to send her prints, but I've been putting off the job. I wanted to do full justice to those rich, impressionistic colors.

I've discovered 'saturation' rendering intent and the colors are fabulous on my Epson 7600. Van Gogh would be proud of them  :D .
Title: ProPhotoRGB
Post by: Ray on August 17, 2005, 04:01:04 am
Quote
A bigger space DOES mean more colors.
A color space doesn't have a bit depth! It's the image that has a bit depth. So the following statement is true: An image with a given bit depth has the same number of tones, regardless of the color space it's in.
This is what I'm having trouble following. As I see it a bigger space does not mean more colours. It means the possibility of colors with greater saturation or intensity. The actual possible number of colors is determined by the bit depth. To put it another way, a 24 bit apple can be cut up into 16.7 million pieces, each piece representing a color. A 48 bit apple can be cut up into 68 billion pieces (is that the right figure?), each piece representing a color. The apple is the same in both cases.

An image with a given bit depth does not necessarily have the same number of tones. Any 48 bit image can have fewer tones than a 24 bit image. It depends on the image.

A 48 bit image has the possibility of a much greater number of tones than a 24 bit image. As I mentioned before, it's a theoretical maximum that could only be realised in a huge image; far bigger than Photoshop could handle.
Title: ProPhotoRGB
Post by: Mark D Segal on August 17, 2005, 02:35:54 pm
Herman, yes that is technically correct as far as the camera and the RAW file go, but once converted to an RGB image with the interpolation that occurs I believe it has the numerical effect of representing the much larger number of potential HSB values, eventhough it doesn't start that way.
Title: ProPhotoRGB
Post by: paulbk on August 03, 2005, 09:49:24 pm
re: ProPhoto as working space
Apparently there’s two schools of thought on this. Some say it’s better to use a ‘working space’ that closely matches that of your output media (paper). That way there’s less compression during the conversion from working space to print space.

Imagine three concentric circles, Small, Medium, Large.
Let:
1) Small represent the color space of your printer/paper combination.
2) Medium represent the MatchColor RGB color space which covers the Small but not excessive margin.
3) Large represent the ProPhoto color space which covers the Small and the Medium but lots of excess margin.

Now if there are 256 shades from the center of any circle to its circumference. Then clearly the Large color space requires more compression to squeeze into the Smaller color space during print rendering. (assume Relative rendering intent) I don't see what's being gained. In fact, if this logic sound (?), you are actually losing tonality. No?

Or, are “we” saying, do the RAW convert in ProPhoto then convert to MatchColor RGB in Photoshop?
Title: ProPhotoRGB
Post by: Ray on August 04, 2005, 11:39:07 pm
Quote
So, unless you are shooting canaries (or more realistically, very unusually intense sunsets - see Figure 6), almost all of the tones you can print or are likely to be able to print in the short to mid term future, are nicely contained within AdobeRGB.
This is an interesting discussion. I don't claim to have any great understanding of color management and color theory. I have Photoshop books on my shelf, and many other books on diverse topics, which I have not found the time to wade through; just peeked at occasionally.

But there are a few apparent facts that leave an impression on my simple mind.

(1) 255,255,0 prints out yellower on premium lustre on my 7600 from the ProPhoto colour space than it does from ARGB.

(2) RGB yellow on the swatches pallette (in PS CS )translates to different combinations of yellow and cyan on the info palette, according to the chosen working space; namely, sRGB 87%Y+8% C; Colormatch 80%Y+6%C; ARGB 97%Y+9%C; ProPhoto 100%Y.

These values are all out-of-gamut, indicated by the exclamation mark, but in relation to the SWOP standard, I assume. But there's a question here that perhaps someone would like to answer.

Now to the canary situation that Paul refers to. The implication is, if your photo does not have exceptionally bright and saturated yellows, then using ProPhoto as your working space will serve no purpose and might even have disadvantages.

Now that certainly makes sense, but have we missed something? Your image might not have (indeed is unlikely to have) a pure RGB yellow. But there might well be other shades, some quite dark even, that require that 100% yellow, in conjunction with the other primaries, that only ProPhoto can deliver.

Another point I'd like to make is in relation to banding in 8 bit. There seems to be some concept that because Prophoto stretches the gamut, the 0-255 values will be wider spaced and we might see gaps.

In defense of this possible downside (not a particularly good defense I might add because I can't now locate the source of the information) my understanding is a typical image in 24 bit color does not contain anywhere near the potential 16.7 million shades of colour. We should remember that this is the pallette to choose from. Any image that was required to represent all 16.7M colors would be of necessity an image in excess of 50MB without any extrapolation. Futhermore, every pixel would have to be unique; ie. a different value of RGB.

In practice, a typical 24 bit image (from vague memory) contains just a few thousand discrete colors. I'm reluctant to put a figure on it, but I think we're talking about 30,000, plus or minus. (Or is that the number of genes in the human genome  :D ).
Title: ProPhotoRGB
Post by: Hermie on August 04, 2005, 05:09:24 am
Quote
Why? The argument for working in 16 bit applies equally to sRGB and ProPhoto.

Does not apply *equally*. In the case of ProPhoto it's not only the extra headroom argument that applies to 16-bit edits. There's an additional argument, because ProPhoto is such a large space you just need more data points to avoid posterization/banding when converting to smaller spaces like sRGB or a printer profile.

Herman
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 06:38:00 pm
The Desaturate feature is a kludge. Yes, you can experiment and probably start to see out of display gamut colors affected while you edit expect the soft proof is now totally off. I don’t know anyone that uses it. Nice try.

I totally gave up on BasICColor based on the behavior of the people running the company. Didn’t even mention them in the book. They run it like a hobby. That said, their chief color scientist (Franz, original from ColorBlind) is a genius and knows his stuff. Can’t write a GUI to save himself but from a technology standpoint, he’s tops. I only wish he’d associated himself with a company that appreciates his talents (someone like X-Rite or GretagMacbeth).
Title: ProPhotoRGB
Post by: Ray on August 06, 2005, 09:37:30 pm
Quote
However, maybe we can develop something practical here.  Would you have a suggestion how to deal with said out-of-gamut colors prior to print?

/> De-saturation by means of the Hue&Sat.-tool (in RGB mode) reduces brightness, too.
/> De-saturation by means of the Hue&Sat.-tool (in Lab mode) changes the hue.
/> The Channel Mixer was recommended elsewhere, but I'm not sure how to use it properly for that purpose.

Any “best practice” how to proceed?
This is a good question. I get the impression some contributors to this thread are in the habit of working with (and printing) out of gamut colors in ARGB and therefore see no point in using a ProPhoto profile which will quite likely increase the number of colors which are out of gamut and the degree to which they are out of gamut.

My understanding is, a monitor is calibrated with respect to a standard such as D65 or D50, not a printer profile. Having gone to the trouble of accurately calibrating your monitor, why would you not want to use proof setup, proof colors and gamut warning prior to printing. If you don't use PS' proof colors and gamut warning for final editing prior to printing, then whether you're in ARGB or ProPhoto you are likely to be sending out of gamut colors to the printer; not only that, the print is unlikely to match what you see on the screen because your monitor wasn't calibrated with respect to any particular paper profile. Is this correct?
Title: ProPhotoRGB
Post by: Mark D Segal on August 06, 2005, 10:36:05 pm
Jeff, we were both replying in parallel and I think what I said is consistent with what you said and our interventions complement eachother to some extent. Please correct me if I am wrong. One major point you made that I find truly interesting is about the reverse table of the printer profile. I am using Epson's PRO4000 Enhanced Matte profile (being the printer and paper combination I use), because going in the forward direction it remains the best of the four different profiles I have had custom-made. Sounds counter-intuitive, but my eyes tell me it is true, and in the final analysis that is what I rely on. Now, I have also found the softproofing using this Epson profile to be "reasonably satisfactory". By that I mean for those images where there is a large shakedown of contrast and saturation moving from the non-proofed to the proofed version on screen, the print definitely prints in the ballpark of the proofed image, but quite often the shake-down in the print is not quite as dramatic as the soft-proofing indicates it will be. This means that when I, say, tweak Curves at the softproofing stage I do need to be a bit careful not to over-compensate. Questions: (i) do you know whether this kind of experience sounds about right for this Epson profile, and (ii) who makes first-class profiles going foreward and in reverse?
Title: ProPhotoRGB
Post by: Ray on August 10, 2005, 10:05:05 am
Quote
That gamut warning is useless. There’s no reason for you to be messing with hue/sat with this overlay. It predates Photoshop’s use of ICC profiles. The profiles will handle the gamut remapping. Using a desaturation technique like this is in comparison like using a kitchen knife as a screw driver.
So now you tell me  ! What is Adobe doing providing a useless gamut warning? I've been relying on that gamut warning to fine tune my images before printing.

The fact is, my Epson 7600 prints out duller images than what I see on the screen but pretty close to what I see with proof setup and simulate paper white. In order to give the images more punch and get them looking more like the image I previously edited without 'proof colors' ticked, I often apply saturation and/or local contrast enhancement to the point where I start getting a gamut warning (grayed out patches). I'll print with a few specks of gray but not large patches of gray.

Are you saying I should just ignore this gamut warning, switch it off and make the colors as bright and saturated as I like?
Title: ProPhotoRGB
Post by: digitaldog on August 11, 2005, 09:50:21 am
Quote
Ray made an interesting point - he says that when soft-proofing, his monitor did not show him the extent of difference in shadow detail that showed up in the prints between two different rendering intents, whereas Gamut Warning did show a difference in the extent of clipping between these rendering intents.
That’s why it’s necessary to:

Setup the soft proof correctly using the simulate check boxes in full screen mode (it produces a more accurate soft proof of the dynamic range of the output)

Insure the output profile is accurate, especially with respect to the soft proof table (the table in the profile that controls the soft proof, not the actual output)

Insure the display profile is good and that the ambient light in the room is matched to display luminance (Lux versus Cd/m2)

That you view the prints under a CCT 5000K box with dimmer that has it’s luminance set to match the display.

Most important in context of using the old Gamut Wanring: be sure the output profile is loaded in a soft proof before invoking. If not, you’re getting a gamut overlay of the CMYK working profile or whatever was last set in Proof Setup. That’s an easy mistake to make. Unlike the Proof Setup where when invoked (Command/Control Y) Photoshop shows you the current output profile being used in the document name, if you just toggle on View-Gamut Warning, you get the overlay but no direct indication of what profile is currently being used for this overlay.
Title: ProPhotoRGB
Post by: Hermie on August 14, 2005, 11:15:22 am
I remember reading a good article on the saturation rendering intent some time ago. Unfortunately I just can't find the link at this moment. The point that the article demonstrated was that sometimes images can benefit from saturation intent. As the implementation of the saturation intent is vendor specific (just as perceptual is) the quality depends on the package used.

At DryCreek e.g. they pay special attention to their saturation rendering intent.
Quote from their website:
"Our newer profiles (August 2004 and later) feature a Saturation intent that is tuned to provide maximum useable saturation in the prints. If an image will benefit from increased saturation, give the Saturation intent a try. Most profiles either reserve the Saturation intent for PowerPoint-type graphics use or simply map it to the Perceptual intent. Our new profiles are designed to give photographers another technique to get the best prints possible."

Herman
Title: ProPhotoRGB
Post by: bossanova808 on August 17, 2005, 03:38:17 am
Talk about pedantry.  Whichever way you shake it 'bigger space = MORE tones" is wrong and "bigger space = different tones" is right.  For any bit depth you care to stick in it!

Anyway, it's a simple point now driven to death so whichever way you choose to say the same thing is fine.  Whatever floats your boat.
Title: ProPhotoRGB
Post by: bossanova808 on August 18, 2005, 04:23:35 am
Good to see we all got there in the end.  One of those we all agree, but are using different words type things that forums really seem to suffer from....
Title: ProPhotoRGB
Post by: Mark D Segal on August 03, 2005, 10:34:12 pm
Paul, my understanding of this is that it is not only the size but also the shape of the colour space that matters, and different printers print diffrerent gamuts. I am informed that the Epson 4000 - and most likely all the more so the new generation of Epson printers - can reproduce certain hues that are within the ProPhoto gamut but outside the Adobe RGB98 gamut. By using the wider gamut you don't run the risk of losing hues that the printer can handle. It seems there is no downside to this.
Title: ProPhotoRGB
Post by: paulbk on August 04, 2005, 04:44:28 am
re: "When converting this 16-bit (actually 12-bit) image to a printer profile the risk of banding is far less."

Why? The argument for working in 16 bit applies equally to sRGB and ProPhoto.

What we need is a 32 bit printer and 64 bit eyes.
Title: ProPhotoRGB
Post by: paulbk on August 04, 2005, 02:59:32 pm
*WAY COOL ALERT*
Interactive Printer, Camera, Scanner, and Monitor Color Gamut Comparisons (http://www.drycreekphoto.com/tools/printer_gamuts/gamutmodel.html)

Quite possibly the coolest tool on the world wide web.
Cancel all appointments. Click. And enjoy!
Title: ProPhotoRGB
Post by: Hermie on August 06, 2005, 05:55:00 am
Quote
>Well, unless you have a new Adobe RGB display, you're STILL not "seeing" everything in the image, what's your point?

You don’t improve anything by adding more unknowns

Not trying to ruffle any feathers here but I'm not going to repeat myself or others. Everything that is relevant in this matter has been said (especially the contributions by Rodney and Schewe). You keep on bringing up this very same argument that has been wiped off the table by numerous replies.

Herman
Title: ProPhotoRGB
Post by: giles on August 06, 2005, 06:34:13 pm
Quote
I actually went to read up on this article and without going to far, found this:

-->All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!

That’s not really so.

[ much text elided --giles ]

So going back to “That is, a bigger colour space does not mean there are more colours in total” the issue here is saturation of the primary colors (RGB in this case). Yes, R255 in sRGB and ProPhoto RGB share the same number but most certainly not the same scale.
So (assuming I'm following correctly) there are "more colours" in terms of a wider range of saturation which you're speaking about.  But there aren't more numbers to represent these colours (Jeremy's "no more colours in total").

In the case where an image fits within the smaller of any two spaces, operations on that image in the smaller space will be capable of finer changes because the steps between (say) R140 and R141 are closer than they are in the larger space.  Finer changes are a good thing, as there is less chance of introducing banding et al ... right?

Giles
Title: ProPhotoRGB
Post by: Mark D Segal on August 07, 2005, 12:53:51 am
Thanks Jeff. I need to check whether my softproofing is paper white/ink black - its late now - tomorrow. Apart from that - yes perhaps if I were totally ISO 3664 compliant the soft-proofing would be very accurate and all would be well until people look at the print outside an ISO bubble. One then hopes the real world wouldn't have violated it too badly!
Title: ProPhotoRGB
Post by: bjanes on August 09, 2005, 10:22:16 pm
I've followed this thread with great interest and have found the discussions very illuminating. I did read a post some time ago by Thomas Knoll on the Adobe MAC PS forum to the effect that he does not recommend ProPhotoRGB for those photographers who lack a basic understanding of color management and rendering intents. Of course, that doesn't apply to any of us in this discussion  :)

As Jeff and Rodney so aptly point out, why throw out colors that you might be able to use at some time or at least control their output? Why not go one step further and use a scene space that preserves more of the full dymanic range of the image? The only such space that I know of is the PhotoYCC that Kodak used for the photo CD, which was proprietary and never caught on, but there must be others. Since they don't seem to be used that much, there must be no advantage but I was just wondering.
Title: ProPhotoRGB
Post by: bossanova808 on August 16, 2005, 10:48:42 pm
Andrew Rodney wrote:

Quote
-->All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!

That’s not really so. This is a fundamental misunderstanding of what a color space is. So I’ll do a quick copy and paste from some text I wrote:

<here follows a recipe for a cookie>

I'm afraid it isn't a misunderstanding, actually a mis-reading.

Far be it from me to argue with someone far more qualified but I'm actually correct here.  I don't really know how to put it in clearer terms - the maths is quite clear.  Each 16 bit colour space has the same total number of tones in it.  What those tones mean is, however, highly variable.  (The 'scale' in your recipe).  

A colour space is simply a definition of the boundaries and they can be as wide or as narrow as you choose - but the number of items contained within these boundaries never changes unless you change the bit depth representing each item.

The rest is up for (seemingly endless) debate but unless I misunderstand binary, the above is just fact.

I don't want to wilfully disagree, and I don't even want to be that involved in the discussion, but I don't think I suffer from any fundamental misundertstanding.  In this case, anyway!
Title: ProPhotoRGB
Post by: Hermie on August 17, 2005, 04:54:22 am
Quote
This is what I'm having trouble following. As I see it a bigger space does not mean more colours. It means the possibility of colors with greater saturation or intensity. The actual possible number of colors is determined by the bit depth. To put it another way, a 24 bit apple can be cut up into 16.7 million pieces, each piece representing a color. A 48 bit apple can be cut up into 68 billion pieces (is that the right figure?), each piece representing a color. The apple is the same in both cases.

With "A bigger space DOES mean more colors.", I meant more colors in the sense of a larger volume/scale in LAB (more saturation etc.).

So I think we are actually agreeing.

>> An image with a given bit depth does not necessarily have the same number of tones. It depends on the image.

Agreed of course.

Herman
Title: ProPhotoRGB
Post by: digitaldog on August 17, 2005, 12:59:16 pm
Quote
Quote
Now if you want to debate that the max red in one color space which is more saturated than another isn’t really “more colors”, OK.
Well, it needs clarifying doesn't it. I get the impression some folks reading this might think a wider range of colors between extremes of saturation translates to a greater number of colors.
Good point. Yes, it’s a tad bit more than semantics. A wider gamut doesn’t provide “more colors” but a wider range of colors. You spread the colors over a wider range and that’s one reason you want to work with high bit data with progressively wide gamut color spaces. And yet the numbers are the same when you define these colors using 256 steps per color channel (for 8-bit). That is R255 isn’t the same color in two different working spaces although they share the same value (which is confusing at first). We’re all used to a unit of something being fixed; “a pint’s a pound the world around.”
Title: ProPhotoRGB
Post by: Mark D Segal on August 11, 2005, 09:39:18 am
Andrew, as a published authority on this subject people in this Forum are looking up to you for real value-added. When you don't read what you are being told and simply talk past the question raised it is helpful to no one.

Ray made an interesting point - he says that when soft-proofing, his monitor did not show him the extent of difference in shadow detail that showed up in the prints between two different rendering intents, whereas Gamut Warning did show a difference in the extent of clipping between these rendering intents. Either this observation occurs under some arcane conditions, or it means that perhaps the Gamut Warning tool should not be relegated to the scrap heap quite so quickly. This is the issue we asked you to comment on. Of course this is a free enclave so you can say you want, but being relevant would be helpful.
Title: ProPhotoRGB
Post by: giles on August 04, 2005, 01:15:56 am
Quote
It seems there is no downside to this.
Offered without comment, since I'm not qualified to comment, but an article discussing potential downsides:

ProPhoto or ConPhoto? (http://www.jeremydaalder.com/singleArticle.php?articleID=6)

Giles
Title: ProPhotoRGB
Post by: Hermie on August 05, 2005, 02:07:01 pm
> What’s amusing are those who say they are preserving colors by working ProPhoto even though they know they can’t print the colors they are “preserving.”

and funny enough the same statement (although to a lessor degree) is true for Adobe RGB.

Herman
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 04:42:13 pm
Quote
You realize that when a photo file color doesn’t map into your print space the rendering process does it for you. In other words, what you see is NOT what you get. You get whatever the rendering process gives you. That’s why in 2005 we still hover over the printer with a fair bit of apprehension to see what it will hatch. We don’t do that with text printers any more because technology has taken the mystery out of it. Back in the DOS days of 6 pin dot-matrix printers it wasn’t so deterministic. Some day fine art printing will be as deterministic as laser jet text is today. But it won’t be tomorrow.
First, with rendering intents to output spaces, you have to decide if you’ll clip the colors or compress them. Also keep in mind that current color management technology only looks at individual pixels and the math involved to do this gamut compression/clipping based on what is basically a solid color (that single pixel). It doesn’t see the image in context. Photoshop and for that matter all color management is just a big calculator that has absolutely no idea about images. An ICC profile simply describes a devices behavior. It “sees” all images the same way (it doesn’t actually see anything but you get the point).

On to soft proofing. You’ve got a emissive display and a reflective print, the dynamic range (contrast ratio) may be totally different, you have an illuminant underwhich you are supposed to view the print (the CMS assumes some viewing illuminant). This stuff is WAY more complex than looking at a page of black text and hoping to see it look exactly like that on a screen (and it will not exactly for reasons I’ve already discussed).

The technology in which color management is based was developed in the 1930’s well before anyone, even science fiction writers had any idea about digital imaging. It looks at how closely two colors match based on how we humans (the standard observer) sees colors. It’s pretty amazing the technology works as well as it does with something as complex as a color image. But it’s far from perfect. We could get closer but users would not be happy if the process was 10X or maybe 100X slower using today’s processors.

Photographers would do far better actually viewing those prints after them come off a printer under a 5000K light box. This would go a long way to helping the color matching issues. When I speak and ask for a show of hands of how many photographers have 5000K boxes for transparencies, I see a lot of hands. When I ask about reflective light boxes, preferably with a dimmer to match the luminance to a display, there are very few. Point is, we can get caught up in all kinds of tiny details about the technology (and the working space) but there are some fundamental simple processes we can all do to get a closer match (like calibrating our displays and doing it correctly). Compared to colors in a working space that fall outside display gamut, this is a MUCH bigger issue to tackle and one anyone with the desire can do.
Title: ProPhotoRGB
Post by: Ray on August 06, 2005, 04:02:09 am
Quote
A)  Make a 1 inch square filled with ProPhoto SATURATED red, R=255, G=0, B=0.
  Send it to the printer using relative rendering intent. It probably doesn’t matter.
C)  You get a 1 inch square of saturated print space red. Not (A) above.
D)  Make a 1 inch square filled with ProPhoto ALMOST saturated red, R=254, G=0, B=0.
E)  You get a 1 inch square of saturated print space red. Not (D) above.
F)  Make a 1 inch square filled with ProPhoto NEARLY saturated red, R=253, G=0, B=0.
G)  You get a 1 inch square of saturated print space red. Not (F) above.
(1) Make a 1" square filled with ProPhoto out-of-gamut saturated red, 255,0,0.

(2) Reduce the saturation till it's just in gamut in relation to, say Epson Premium Glossy with a Bill Atkinson profile.

(3) Read the proof RGB values on the info pallette and you'll find that 255,0,0 has been transformed into something like 255,46,139.

This is the maximum red saturation that the printer/paper/profile combination can sustain and it's a slightly magenta-ish red as opposed to the more yellowish ARGB maximum red.

Is this what you're getting at, Paul  :) .
Title: ProPhotoRGB
Post by: PeterLange on August 06, 2005, 07:12:13 pm
Quote
By the time an output profile “gets” data, it’s gone through the PCS and is in LAB. So if I’m understanding where you’re coming from, I'd say again that the output profile has no real idea what the incoming data is as far as the original RGB color space (sRGB, ProPhoto etc). ...
  

That is correct and completely understood.  The final printer/media profile is “ignorant“, but the guys who construed the profiling SW + the implementation of the Perceptual intent are certainly not.

PCS Lab is huge, whereas printer/media profiles are small (deltaE3-wise).  If you’d just scale down / compress the whole volume of CIE Lab into such a “poor” output space, all in-gamut colors would get altered and de-saturated in an unacceptable way.  Therefore a nifty non-liner algorithm for compression is required.

In this context an assumption about the most likely source space is made (could also be more than one) by these guys.  While collecting the colors from PCS Lab, all colors outside the range of this assumed source space are somehow clipped & merged in a RelCol manner.  All colors ranging in-between this assumed source space and the output profile are gently squeezed in … AFAIK.

So my initial question was not rhetoric at all.  If the Perceptual intent of a printer profile was not prepared for ProPhotoRGB, results are not much different compared to RelCol.

That’s at least what I see when working with quite saturated colors in a large working space.  In both cases, Softproof as well as print show a lack of details due to posterization (unless some time is invested to tame these out-of gamut colors).



Quote
There’s only one rendering intent (actually one table, two intents) you can use with matrix profiles (Adobe RGB (1998), ProPhoto etc) and that’s colorimetric. ...
  

That is correct, but can be misleading.  It is the reason why I added above reference to ICC White Paper #2 http://www.color.org/ICC_whi....ses.pdf (http://www.color.org/ICC_white_paper_2_Perceptual_rendering_use_cases.pdf)
(of course I know yours, too).

A proprietary color management system (CMS) can / could anytime realize a Perceptual compression between two matrix spaces, such as the input profile of a Camera and the preferred output space like Adobe RGB.  In all probability, that’s what happens “in-camera” when you shoot sRGB/aRGB/JPEG/TIFF … AFAIK.

I see no restriction in principle why a Raw converter shouldn’t offer such a perceptual rendering option (optionally).  Minor tradeoffs would be acceptable if this saves me time.  Current philosophy of “preserving everything in ProPhotoRGB” leaves the whole down-sizing / de-saturation to the operator or the printer profile.  And here we are moving in a circle………


However, maybe we can develop something practical here.  Would you have a suggestion how to deal with said out-of-gamut colors prior to print?

/> De-saturation by means of the Hue&Sat.-tool (in RGB mode) reduces brightness, too.
/> De-saturation by means of the Hue&Sat.-tool (in Lab mode) changes the hue.
/> The Channel Mixer was recommended elsewhere, but I'm not sure how to use it properly for that purpose.

Any “best practice” how to proceed?

Peter

--
Title: ProPhotoRGB
Post by: Schewe on August 06, 2005, 11:51:54 pm
Quote
By that I mean for those images where there is a large shakedown of contrast and saturation moving from the non-proofed to the proofed version on screen, the print definitely prints in the ballpark of the proofed image, but quite often the shake-down in the print is not quite as dramatic as the soft-proofing indicates it will be. This means that when I, say, tweak Curves at the softproofing stage I do need to be a bit careful not to over-compensate. Questions: (i) do you know whether this kind of experience sounds about right for this Epson profile, and (ii) who makes first-class profiles going foreward and in reverse?
Greytag & Monico/X-rite (the current software packages) both produce pretty good profiles that go both ways well.

If you are finding that the softproofed image using the absolute colormetric method (paper white/ink black) are not accurate, then I suspect you are not yet skilled in using softproofing, or your profiles' reverse tables (the part that is used when softproofing) aren't great.

One factor that is critical to accurately using softproofing is that your entire display environment is controled and accurate and that you have a good print viewing device.

My entire computer imaging area follows the ISO 3664 standar for viewing conditions for graphic technology and photograpy. Sorry, since it's an ISO copyrighted PDF, I can't share it, but basically, the viewing requires a specific ambient luminance, neutral sounds, specific D65 white point of the display, and a specific luminance of the display.

Once you achieve that, and presupposing and accurate display profile correctly used, the softproofing environment pretty much requires that you work in Photoshop in a full screen mode with all the interface of Photoshop hidden by the tab key. This important so that the non-image portions of the display do not influence your eyes.

The viewing device also needs to be to a stanard-I use a digital GTI viewing box set at a 90 degree placement from the display so O can't see both the display and the viewing box at the same time-it forces you to visually toggle between the display and the print.

Properly set up and deployed, the softproofing in Photoshop is scarey accurate for both inkjet as well as halftone proofing.

It works, and works very well to accurately predict, on screen, what your print will look like-regardless of the original color space.
Title: ProPhotoRGB
Post by: Hermie on August 04, 2005, 04:32:01 am
Quote
Andrew Rodney's reply is key here:

"Yup, if in ACR I see clipping in say Adobe RGB (1998), I'll go directly to ProPhoto."

Paul, my point is, and that is I believe what Rodney says, it depends on the image. I don't disagree on that.

Quote
All you get is 256 tones REGARDLESS of the color space (sRGB, Adobe1998, or ProPhoto). Stretch 256 tones over a large color gamut and banding could be troublesome.

That is why you should work in 16-bit with ProPhoto RGB. That way there are 4096 tones stretched over the wide ProPhoto gamut (with a camera capturing 12-bits). When converting this 16-bit (actually 12-bit) image to a printer profile the risk of banding is far less.

Herman
Title: ProPhotoRGB
Post by: Mark D Segal on August 04, 2005, 03:47:17 pm
Paul, thank you so much for that link to Dry Creek's model. It is indeed most cool, and does give food for thought about how much difference these color spaces make by the time you get to the printer. I think I remember once posting something on one of these threads in LL to the effect that printing remains the determinative weakest link in our digital imaging chain, despite the impressive quality we can get from the most recent generations of inkjet printers.
Title: ProPhotoRGB
Post by: Ben Rubinstein on August 05, 2005, 10:03:36 am
Just had a look at that program. How utterly horrible. Not the program but how little of my Canon 1Ds colour space the Fuji Frontier printing on their pro paper (which I use) can print, infact I would say plenty less than 50% OUCH!
It doens't measure up that well against the sRGB gamut either.
The epson doesn't seem that much better, not good enough to be worth the time, bother and expense.

Based on that premise, maybe my above post does'nt make that much sense, if I'm losing that much anyway from the camera through to print, I may as well work in ProPhoto and convert at the end, a conversion is taking place anyway so why not give it the maximum amount of information to convert down?
Title: ProPhotoRGB
Post by: Ben Rubinstein on August 07, 2005, 07:19:06 pm
Bloody ####, I'm going back to film, I was happy enough in those days....
Title: ProPhotoRGB
Post by: Mark D Segal on August 08, 2005, 07:51:11 pm
Hi Peter - I never assumed you had any marketing mission, and neither do I. This is just an interesting technical discussion that should help us better understand what we are doing.

I did have a second look at page 7. What I see there is that between Andrew Rodney and Jeff Schewe your points have been addressed, and nothing yet really responds to my last post that you quoted; however, to my way of thinking, that is the nub of the matter in this thread.

Andrew's response to Ray to-day is very sensible, but it deals with varying impacts of different rendering intents, whereas the issue at stake in this discussion thread is whether there is a differentially worse impact from the use of whatever rendering intent when the working space is Prophoto rather than ARGB98. (Remember this whole debate "gathered steam" over the question of whether there are "downsides" to working in ProPhoto!)
Title: ProPhotoRGB
Post by: Ray on August 09, 2005, 09:00:08 pm
Quote
Quote
The paper doesn’t really matter, however, the scenario is clearer because the sRGB JPEG file is completely in-gamut now.  Whereas the ProPhotoRGB file shows many many out-of-gamut marks with regard to the printer profile.

Do I take it this is how you printed both images (or would print both images), one out of gamut, the other in-gamut?

Any image with out-of-gamut colors is likely to lose detail within those particular shades that are out-of-gamut. The question here of main interest to me is, having brought those bright yellows (just) into gamut in both images, sRGB and PP, how do the yellows compare when printed?

I don't like printing images when I know they are out-of-gamut. I don't trust either perceptual or relcol to do the right thing, but I might do some further experimentation with these rendering intents when I get back to my printer.
Title: ProPhotoRGB
Post by: digitaldog on August 10, 2005, 09:01:04 am
Quote
Quote
I’m not sure what you mean “the sRGB image required less desaturation”.
The sat slider of the PS hue/sat tool required less adjustment to remove all of the grayed-out areas (-68 for sRGB as opposed to -71 for the ARGB image and -62 for PP), all in relation to the Bill Atkinson Prem Gloss profile.
That gamut warning is useless. There’s no reason for you to be messing with hue/sat with this overlay. It predates Photoshop’s use of ICC profiles. The profiles will handle the gamut remapping. Using a desaturation technique like this is in comparison like using a kitchen knife as a screw driver.

Is it me or is the server running these forums really dog slow???
Title: ProPhotoRGB
Post by: Ray on August 17, 2005, 12:26:01 am
Quote
As the author of the original article I just want to clarify one thing:

Andrew Rodney wrote:

Quote
-->All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!

That’s not really so. This is a fundamental misunderstanding of what a color space is. So I’ll do a quick copy and paste from some text I wrote:

<here follows a recipe for a cookie>

I'm afraid it isn't a misunderstanding, actually a mis-reading.

Far be it from me to argue with someone far more qualified but I'm actually correct here.  I don't really know how to put it in clearer terms - the maths is quite clear.  Each 16 bit colour space has the same total number of tones in it.  What those tones mean is, however, highly variable.  (The 'scale' in your recipe).  

A colour space is simply a definition of the boundaries and they can be as wide or as narrow as you choose - but the number of items contained within these boundaries never changes unless you change the bit depth representing each item.

The rest is up for (seemingly endless) debate but unless I misunderstand binary, the above is just fact.

I don't want to wilfully disagree, and I don't even want to be that involved in the discussion, but I don't think I suffer from any fundamental misundertstanding.  In this case, anyway!
I'm not sure what the point is that's being made here. It's clear that changing the bit depth from say 8 bit per channel to 16 does not increase the maximum saturation of any particular color (and therefore does not change the gamut)but it does allow for the possibility of a greater number of tones. It's just that the increment between one tone and the next can be made smaller, but it doesn't have to be smaller. A 48 bit image has the possibility of several billion colors instead of the mere 16.7 million limitation of a 24 bit image. But those are maximum numbers. The actual number of discrete tones in a real world image is likely to be considerably less than 16.7 million whether it's a 24 bit or 48 bit image.
Title: ProPhotoRGB
Post by: Jonathan Wienke on August 05, 2005, 06:55:26 pm
Quote
Why should any one edit using colors they can not print, today?
Let's turn it around: What's the point of deliberately crippling an image with the limitations of a print technology that may be irrelevant tomorrow? It makes much more sense to edit an image to what you want it to be, and dumb it down to the output device on a case-by-case basis (making an output-device-specific copy if necessary) rather than editing within the constraints of one particular output device and having to re-process from the RAW if a better printer comes along.
Title: ProPhotoRGB
Post by: Mark D Segal on August 10, 2005, 12:46:46 pm
OK, in an indirect way you've answered my question in the first line. At the soft-proofing evaluation stage we are only talking about viewing, not converting data in any final sense of the term. Thanks. And I much prefer this to Gamut Warning too.
Title: ProPhotoRGB
Post by: digitaldog on August 11, 2005, 08:48:04 am
What’s the point of seeing via an ugly mask showing you what you can’t print when you can see via a soft proof exactly what you’ll get?

Even if you were so skilled and patient to desaturate the mask (out of gamut colors) to the degree you’d be able to with the output profile (doubtful) you’d be in the same position; an image with a gamut mapped to the printer. Using a good profile/rendering intent or scrubby with a sponge tool, the out of gamut colors can’t be printed! This isn’t like Spinal Tap; there’s not 11 on the volume control.
Title: ProPhotoRGB
Post by: jani on August 17, 2005, 04:44:49 am
Quote
A 48 bit apple can be cut up into 68 billion pieces (is that the right figure?),
No, that's not the right figure.

2 to the power of 48 is:

281 474 976 710 656

Quite a bit more than 68 billion, regardless of whether you're British or not. ::

Edit:

2 to the power of 36 is approximately 68 billion, though.
Title: ProPhotoRGB
Post by: Hermie on August 17, 2005, 02:14:48 pm
Quote
Turning to capture devices, the maximum number of individual HSB values any pixel represented by the photosites in the sensor can capture depends on pixel bit depth. For example, a Canon 1Ds has a sensor of bit depth = 12, hence each pixel can theoretically contain any one of 68.7 billion hues [(2^12 per channel)^3 channels]. But since there can be only one HSB value per pixel, the maximum number of different HSB values the image will contain depends approximately on the sensor's pixel dimensions: e.g. on the Canon 1Ds 11.1 MP.
Digital camera's (except those equiped with Foveon sensors, e.g. Sigma/Polaroid) do not capture colors. They capture/measure light intensity in a linear fashion. The colored filters on top of the sensor pixels filter colors (e.g. red filter absorbs cyan (=green+blue) and only red passes through). Color (RGB values) is reproduced through interpolation (demosaicing). So a camera with a 12-bit A/D converter is capable of capturing 2^12= 4096 tones per sensor pixel. Thats is why the image size of raw files is approximately 1/3 of normal RGB image. In the raw file there's only one channel of information (intensity).

Herman
Title: ProPhotoRGB
Post by: paulbk on August 04, 2005, 01:23:26 am
giles, thank you! The link article you point to is excellent.
Everyone should read this:
ProPhoto or ConPhoto? (http://www.jeremydaalder.com/singleArticle.php?articleID=6)

Try this. -- Pick a file with a wide color range with some colors known to be out of gamut. If the file is not already in ProPhoto then “Assign it” to ProPhoto and do a soft proof using the printer profile you plan to use and turn on Gamut Warning. Observe. Now Assign the same file to MatchColor. Much less out of gamut colors.

I did this with Bruce Lindbloom’s 16 million color tif file using a professional Hahnamühle Rag printer profile. You will be amazed how much is out of gamut using ProPhoto.

Clipping during RAW conversion is a judgement call. It may be better to clip once and work in a color space the fits your output device than to suffer the *compounding problems* Jeremy Daalder points out in the linked paper.
Title: ProPhotoRGB
Post by: Ben Rubinstein on August 05, 2005, 10:32:12 am
I'm wondering whether I will see any difference now, I can always change the settings late I know.  I ran a comparison just now of a typical picture that I take, a bride next to some bright orange and red flowers. I opened one as sRGB 8bits which is what I usually use for proofs, the other at Prophoto 16bit, converted in PS to sRBG 8bits. Yes there is a difference, whether it's enough to bother with, that I have to do more testing for. What worries me is that the entire picture looks different in terms of highlight 'brightness' and contrast/saturation. What I am seeing in ACR when using prophoto is not what I'm seeing in PS once the picture is converted to print.
Soft proofing means that I edit in one colour space, work in the same space in PS, convert to a printable colour space, soft proof and spend time making it look like it did before.
I might as well do the whole thing in the printable colour space so that when it is right, it's right  and I don't need to tweak the picture again after having spent hours getting everything just right. Especially as you can't sharpen as an adjustment layer  :p  Futhermore Soft Proofing may be a solution for the fine art landscape photographer. For everyone else who does 90% of the post work in ACR and batches the rest it is not a viable option, I want my final product to look like it did on screen. At present I do get that....
Title: ProPhotoRGB
Post by: paulbk on August 05, 2005, 04:42:50 pm
Rodney,
Don’t delete the RAW keepers. I often go back and reedit my original RAW capture as the technology improves as well as my skill. And since my skill is two clicks from none, I have lots to look forward to..

Why should any one edit using colors they can not print, today?
Title: ProPhotoRGB
Post by: PeterLange on August 06, 2005, 03:05:47 am
Quote
Quote
Quote
First, with rendering intents to output spaces, you have to decide if you’ll clip the colors or compress them. ...
Just a friendly question:
 
Are there any printer profiles
which support Perceptual rendering in way
which assumes that the source space was ProPhotoRGB?

Peter

--
No. Output profiles don’t have any idea when built what the source color space will be.
 

Doesn’t the profiling software implement the Perceptual intent
and its non-linear transforms
based on a on a silent assumption about the source color range?

Peter

---
Title: ProPhotoRGB
Post by: Hermie on August 07, 2005, 01:18:24 pm
Quote
The main parameters for calibrating a monitor are the white point, black point and gamma. Once these are set, profiling is done to measure the numerical differences between the (correct) data describing the color reference patches of the profiling software and the (perhaps incorrect) values the monitor shows them as. These measurements are then used to create a profile that neutralizes these differences so the monitor shows the colors of the file data. Likewise the printer profile measures and neutralizes differences between the (correct) data in the software file for each patch on the profiling target and the (perhaps incorrect) numerical values the printer prints them at. (Both sets of profiles calculate interpolations for all the data between these reference points.)
A bit OT but, generally this works just a bit different, it does NOT measure the numerical differences between the (correct) data describing the color reference patches of the profiling software and the (perhaps incorrect) values the monitor shows them as

Generally monitors/printers are fed with input signals (just numbers without any perceptual meaning, e.g. RGB(255,0,0). Remember you have to turn off color management when sending patches to a printer, it's all about the numbers. The devices response to these input signals is measured in device-independent (or colorimetric) color coordinates and is used to create the forward (A2B) table and inverse (B2A) table (computational step) or matrix.

Herman
Title: ProPhotoRGB
Post by: PeterLange on August 08, 2005, 06:32:58 pm
Quote
Peter - fine, the same thing with added detail, but so what? The bottom line is that anyone claiming a significant downside to working in Prophoto color space needs to demonstrate in normal photographic prints that rendering intents have a differentially negative impact on posterization as you move from smaller to larger embedded or working color spaces relative to the (fixed size) output color space. It is not clear in principle and where is the practical real-life evidence?
Mark,

Now after we have talked about RelCol (posterization / channel clipping), please have a second look at my initial posts at page 7.  Just give it a chance. I have no marketing mission to argue someone into anything.

Cheers! Peter

--
Title: ProPhotoRGB
Post by: digitaldog on August 09, 2005, 01:19:38 pm
Quote
Andrew, thanks - now we're getting down to where the rubber hits the road. Is it correct to infer from your reply that one should NOT USUALLY see in a print, for example, increased posterization because of the fact that ProPhoto has more "invisible colors" at play than ARGB98?
Depends on a number of factors. The Synthetic image shows you things you can’t see on real world images or might show up if you just happened to have an image that had color and tone that contained problematic areas. You might never see the issues unless you got lucky (or unlucky). On the other hand, the synthetic image is only useful in showing some things. For example, going to the Dan Margulius “test” rules for evaluating the usefulness of 8 versus 16-bit, a synthetic image is a no/no. However, such an image might very well show the effect of quantization errors. Yes, you may never see this show up in a real image but the errors are still there. That’s somewhat useful. It may not be “real world” but it does provide a wealth of information.

ProPhoto has non visible colors! To make the size it needs to be, the primary colors had to be stretched to the point the blue primary falls off the CIE chromaticity diagram!
Title: ProPhotoRGB
Post by: bossanova808 on August 17, 2005, 01:46:43 am
The point was only that Andrew mis-read the article, perhaps didn't read it, and claimed there is a fundamental mis-understanding of colour spaces in the quote - which there isn't.

You're just re-stating the point - that it is the gap between tones, and what those tones mean (ie how the numbers are tied to concrete colours), that changes in a colour space, NOT the total number of tones.

What inferences should be drawn from said point is up to you.

That's all!  I certainly wasn't taking on the whole thread - I'd rather be doing some real work!
Title: ProPhotoRGB
Post by: Hermie on August 04, 2005, 02:26:42 am
Quote
paulbk wrote: Bottom Line: Being able to "see colors on a monitor" is self-deceit if your intention is to make a print. And for me, it is ALL about the print.

and by using ProPhoto RGB you are actually using your printer's full gamut. I agree with Mark saying that "printers can reproduce certain hues that are within the ProPhoto gamut but outside the Adobe RGB98 gamut. By using the wider gamut you don't run the risk of losing hues that the printer can handle."

See e.g. this graph that'll show the relationship between camera, monitor, printer and working spaces:
http://www.xs4all.nl/~teeuwen/ColorThink%20Graph.jpg (http://www.xs4all.nl/~teeuwen/ColorThink%20Graph.jpg)
It's all about the small triangle on top of the Artisan profile:
Adobe RGB clips some camera colors, especially dark greens/yellows that you see frequently in foliage. Although your monitor cannot show these colors, the Epson R800 for example can print them.

Herman
Title: ProPhotoRGB
Post by: Mark D Segal on August 05, 2005, 10:07:12 am
Suppose one day you change printers, get one with a different and wider color gamut and you want to make better prints of some older files - you would need to have had the benefit of the additional information. As well, you can visualize data loss within PS before printing by soft-proofing with your printer profile in the soft-proof set-up, allowing you to make last-minute adjustments if you don't like what you see.
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 04:49:40 pm
Quote
Rodney,
Don’t delete the RAW keepers. I often go back and reedit my original RAW capture as the technology improves as well as my skill.

Why should any one edit using colors they can not print, today?
Delete them, never. In fact my big decision today is do I want to fully embed the original RAW in my .DNG’s or not. Bigger file and I have a lot more confidence in .DNG but it’s hard to get past the idea of throwing away the actual original data.

However, once I process my RAW data into a wide gamut, high bit archive, I really don’t want to go back to the RAW/DNG unless there’s a gun to my head. Yes, as RAW converters get better so can the rendered data. But I’d rather if possible go to the actual image data (the rendered and encoded file in ProPhoto) and work from that. I’ll do capture sharpening, clean up whatever needs to be done and consider that my “transparency” to use for all subsequent uses. I can go back to the “Negative” and make a “new print” so to speak but I’d rather not.

By starting the process by going into a wider gamut working space, there are fewer reasons I’d go back to the RAW.

There may be colors today I can use but that device may not be sitting on my desktop. I don’t own a LightJet (as well as a lot of really nice output devices) and it’s possible I might want a print in a week that has a wider gamut than what I have on my desktop. It’s not like I have to way 5 years.
Title: ProPhotoRGB
Post by: paulbk on August 06, 2005, 12:22:32 am
>Well, unless you have a new Adobe RGB display, you're STILL not "seeing" everything in the image, what's your point?

You don’t improve anything by adding more unknowns.

>Actually, testing has indicated that there is potentially a Delta E of up to 2+- even sending the same file to the exact same printer/paper combo, even on the same day. There's built in variability (read chaos) in most anything...

From a practical point of view I agree there’s variability in the mechanical performance. That’s a manufacturing QA issue. Not much we can do about it except keep the nozzles clean and aligned etc. I’m talking about the digital process. Send the same file to a printer and the printer receives the same set of ones and zeros in exactly the same sequence. The nozzles fire in exactly the same sequence. Etc. You get the same print within the manufacturing/repeatability tolerance of the printer.

>have no idea what you are talking about. . .wanna take another whack at it?

A)  Make a 1 inch square filled with ProPhoto SATURATED red, R=255, G=0, B=0.
  Send it to the printer using relative rendering intent. It probably doesn’t matter.
C)  You get a 1 inch square of saturated print space red. Not (A) above.
D)  Make a 1 inch square filled with ProPhoto ALMOST saturated red, R=254, G=0, B=0.
E)  You get a 1 inch square of saturated print space red. Not (D) above.
F)  Make a 1 inch square filled with ProPhoto NEARLY saturated red, R=253, G=0, B=0.
G)  You get a 1 inch square of saturated print space red. Not (F) above.

Now you’ve sent three different files to the printer and you got the same print each time. And this series is almost endless. You are going through motions in the belief your efforts will have some real effect. When in fact they will not. I call that a religious experience.
Title: ProPhotoRGB
Post by: Mark D Segal on August 07, 2005, 01:37:22 pm
Herman, yes that is a more precise description of what I was getting at.

Peter Lange: further to my previous post I should have mentioned one could also adopt a workflow whereby one insures all colors are in gamut by having the gamut warning turned on (this only works properly with soft proofing set-up) and adjusting everything so nothing is "greyed out" (if grey is the color selected to illustrate out of gamut stuff). However - the point relevant to this thread is that this procedure does not become any more or less useful as a function of the chosen color space.
Title: ProPhotoRGB
Post by: Hermie on August 08, 2005, 01:20:41 pm
Quote
You might want to try this on a synthetically constructed image like a Granger Rainbow.
you can download a Granger Rainbow from:

http://www.colorremedies.com/realworldcolor/downloads.html (http://www.colorremedies.com/realworldcolor/downloads.html)
Title: ProPhotoRGB
Post by: Mark D Segal on August 09, 2005, 01:07:29 pm
Andrew, thanks - now we're getting down to where the rubber hits the road. Is it correct to infer from your reply that one should NOT USUALLY see in a print, for example, increased posterization because of the fact that ProPhoto has more "invisible colors" at play than ARGB98?
Title: ProPhotoRGB
Post by: Hermie on August 17, 2005, 02:31:28 am
Quote
The point was only that Andrew mis-read the article, perhaps didn't read it, and claimed there is a fundamental mis-understanding of colour spaces in the quote - which there isn't.

You're just re-stating the point - that it is the gap between tones, and what those tones mean (ie how the numbers are tied to concrete colours), that changes in a colour space, NOT the total number of tones.

What inferences should be drawn from said point is up to you.

That's all!  I certainly wasn't taking on the whole thread - I'd rather be doing some real work!
There IS a fundamental misunderstanding in Daalder's quote:
"All colour spaces of the same bit depth (typically 8 or 16 bit) have the same total number of tones. That is, a bigger colour space does not mean there are more colours in total!"

A bigger space DOES mean more colors.
A color space doesn't have a bit depth! It's the image that has a bit depth. So the following statement is true: An image with a given bit depth has the same number of tones, regardless of the color space it's in.

Herman
Title: ProPhotoRGB
Post by: Mark D Segal on August 04, 2005, 09:59:20 am
Thanks for the reference to the Jeremy Daalder article which I read with interest. But I am not convinced. Firstly, I work in 16 bit mode, so anything that can happen in 8 bit mode is of no concern. Secondly, I have been using ProPhoto for months with a variety of photos, some with deep shadow areas, and I have observed ZERO banding of anything anywhere in the printed output. I look upon using ProPhoto as an insurance policy. Just in case there are some ProPhoto hues - say deep yellows or magentas - that my 4000 can print - I haven't sacrificed them by confining myself to AdobeRGB98. This might not sound as scientific as the Daalder article, but I think it makes practical sense.
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 01:02:25 pm
Quote
Correct me  if I'm wrong, and I think that this is what Paul has been saying all along. If my prints are made on a Fuji Frontier which prints to the sRGB colour space, then does it not make more sense to work in that colour space  from the beginning of my workflow so that I am not assuming certain saturated colours are contained in ACR using prophoto and then converting to the print colour space of sRGB just before sending to print, losing the saturated detail and having to start again.
The Frontier does not, repeat does not print to sRGB. It assumes all files are in sRGB to convert to it’s output color space.\

There’s only one output device on the planet that output’s sRGB. That’s a display that fully follows the specifications (down to the ambient light in which the display resides) of sRGB.
Title: ProPhotoRGB
Post by: PeterLange on August 05, 2005, 05:23:17 pm
Quote
First, with rendering intents to output spaces, you have to decide if you’ll clip the colors or compress them. ...
Just a friendly question:

Are there any printer profiles
which support Perceptual rendering in way
which assumes that the source space was ProPhotoRGB?

Peter

--
Title: ProPhotoRGB
Post by: Schewe on August 05, 2005, 11:34:09 pm
Quote
Aside: “using Soft Proofing correctly, you can be about 90% accurate in your visual predictions on-screen to print.”
As I said, using a large color space puts the fun and intrigue back in printing.

Well, unless you have a new Adobe RGB display, you're STILL not "seeing" everything in the image, what's your point?

Quote
Seen from a different point of view: If you send the same file to the printer you get the same print every time.

ding, sorry, thank's for playing our game...

Actually, testing has indicated that there is potentially a Delta E of up to 2+- even sending the same file to the exact same printer/paper combo, even on the same day. There's built in variability (read chaos) in most anything...

Quote
Even if half the pixels are out of print space gamut. The print process is deterministic going one way. But the reverse is not true. If you could run time backwards and feed the same print into the printer you will not get the same file every time. Because there is only one in gamut file and many many out of gamut files that will render to the same print.

I have no idea what you are talking about. . .wanna take another whack at it?
Title: ProPhotoRGB
Post by: Schewe on August 06, 2005, 10:09:31 pm
Quote
Any “best practice” how to proceed?
Yes, use Photoshop's softproofing to see what the heck the image will look like when printed, pick the best rendering intent for the image and under softproofing, adjust the image to achieve the results you want.

It really isn't all that hard folks...a lot of what has been talked about here is really pointless-what matters is what the heck does the image look like when reproduced in its final form-and that all comes down to learning how to softproof. If you have a 90% accurate prediction, on screen, of the dynamic range and color of the final print, anybody with "decent" Photoshop tone and color adjustment skills can learn to nail the final output if not on the first print (which to be honest is about where I am "most" of the time) or with one single iteration.

Also, just to be absolutely clear-it doesn't matter a bit to an output profile, what the incomming color is...profiles go from the interchange space (usually but not always Lab) to the output space via a rendering intent. Whether the original data is comming from sRGB, A RGB or PP RGB doesn't matter one bit. What DOES matter and matter a lot is the quality of the output profile in terms of the interchange to printer side as well as the interchange to display side. Many profiles can be used to do a decent job of transforming from the working space to the printer space but the reverse tables suck and those profiles are useless for softproofing.
Title: ProPhotoRGB
Post by: Schewe on August 07, 2005, 03:11:15 pm
The problem with the Out of Gamut Warning is that while it tells you what colors are in/out of gamut, it doesn't tell you by how much. It only indicates that it's out. Also, it doesn't tell you how the resulting out of gamut clip/compression will effect you image.

Out of Gamut Warning is a much older tool in Photoshop than the softproofing function. As such, Out of Gamut is pretty old tech. The real way to deal with out of gamut colors is to view them in the softproofing environment to see what visual effect will result in the clip/compression of out of gamut colors and allow YOU to choose how to handle it.
Title: ProPhotoRGB
Post by: digitaldog on August 08, 2005, 11:35:07 am
Quote
The last time I tried to do some comparison print tests between perceptual and relative colorimetric with an image with out of gamut colors, I couldn't see any differences.
You might want to try this on a synthetically constructed image like a Granger Rainbow (easier but not as effective, a good old spectral gradient).

Advantage; you’ll see every tiny bit of difference on such an image. You can build the image in LAB then convert to sRGB, Adobe RGB (1998), ProPhoto RGB or just assign new working spaces to the image in one of those RGB color spaces (the numbers don’t change so it doesn’t matter). What’s interesting is to see how the source profile affects the final. That is, the numbers in a duplicate file are identical but by assigning sRGB or ProPhoto RGB and converting to the same output profile, you’ll see differences and how the source plays a role.

Disadvantage is this isn’t a real image. However, when you see banding or other issues in such an image, it does indicate it IS possible to see this in a real world image! I recently did a lot of testing of two profile packages using this and real world images. We were trying to see the effect of smoothing on the output profile. On even a good deal of representative test images, it wasn’t always that visible where there were issues with the profiles. IF the image had a certain range and saturation of color somewhere in it, you could make out a slight difference. With the synthetic image, it jumps off the page!

So what does this tell us? Real world images are what we all work with. However, it’s often the case that issues like banding or smoothing issues will not be seen in some images, will be seen slightly in others and look pretty obvious in yet other real world images. It’s kind of a crap shoot. With a synthetic image, there’s no ambiguity what’s going on.

Like the other post in this forum about LAB conversions, there are those that say “you can’t see the effect of this or that.” That is somewhat valid but we never know when we could get bit in the butt based on image content (and the output device). The data loss or issues are still there, so if we can’t see them, does that mean we should ignore the issues or pretend they may not crop up later?

So using synthetic images has some merit just don’t put a huge amount of concern in the results all the time. Ideally, test with both types of images. They both tell you a lot about a process!
Title: ProPhotoRGB
Post by: PeterLange on August 09, 2005, 04:36:55 pm
Quote
 
O.k. Mark,

Here we go. Today I started out to capture the famous yellow flower (at sunny daylight); colors even fall out-of-adobeRGB.  In fact, I made two shots: sRGB JPEG and Raw.  The Raw file was processed at camera-default settings to ProPhotoRGB, 16 bit.  The only manipulation involved (by purpose) was that I set all sharpening to zero; in-camera as well as in ACR.

Both files were soft-proofed to an Epson premium glossy profile.  The paper doesn’t really matter, however, the scenario is clearer because the sRGB JPEG file is completely in-gamut now.  Whereas the ProPhotoRGB file shows many many out-of-gamut marks with regard to the printer profile.

Surprisingly, the sRGB JPEG file shows much more details (at 200% magnification), whereas the ProPhotoRGB file shows posterization.  Changing the SoftProof from RelCol to Perceptual helps, but not perfectly.

How can this be? It seems to me that the in-camera conversion & gamut compression to sRGB is somehow realized by a proprietary perceptual algorithm. No / less channel clipping, unlike RelCol. Remember, if the color engine supports this, it’s even possible between matrix spaces (afaik). If someone knows more, please post. Finally, saturation is sacrificed while details are maintained.
Also, it’s obvious for me that the Perceptual intent with the printer profile does not differ enough from RelCol to deal with such remote out-of-gamut colors from ProPhoto RGB.


This does not claim to be a scientific test.  Equipment or whatever may play a role. Others may get different results or see things differently. A round-robin test could help.  Also I desisted from any image editing, which of course requires only basic PS skills to realize a perceptual de-saturation by hand.


Do I like the results – no.
Do I want to go back to sRGB JPEG – no.   
Am I missing something here – can’t exclude!
Do I go on holiday now – yes, soon  .

Cheers! Peter

--
Title: ProPhotoRGB
Post by: PeterLange on August 13, 2005, 08:17:52 am
Following please find an early article by Bruce Fraser, where he exactly describes the problem which I encountered:

Extracted from:  “Out of Gamut: Exploring Wide, Open (Color) Spaces”
http://www.creativepro.com/story/feature/8582.html (http://www.creativepro.com/story/feature/8582.html)
(Bruce Fraser, Sept. 2000)

“A second problem arises with the Perceptual rendering tables built into most output profiles. All Perceptual tables contain an assumption about the source space: Some profiling tools, notably Pictographics' ColorSynergy, actually allow you to choose a source space, but most use a hardwired assumption. Few if any use a space anywhere near as large as either EktaSpace or ProPhotoRGB, so the default gamut mappings may not work all that well.

You can get around this -- very successfully, I may add -- by working inside a simulation of your output space and adjusting the colors in the source image to achieve the appearance you want. Photoshop 6.0, which should ship in the next few weeks, offers better output simulations than any previous version, and lets you preview RGB output as well as CMYK. So you can regard the gamut mapping issue as a blessing and a curse. The blessing is that you can control the mapping of the colors in the original to your output. The curse is that you have to.


For further theory just follow my posts from page 7.  Finally, I just can recommend to try the real-world tests which I suggested at page 10:  Capture an intensive yellow flower at sunny daylight.  Make two shots: sRGB JPEG and Raw.  Process the Raw file in the way you prefer to ProPhotoRGB.  Softproof both files to your preferred printer profile (or make tests prints) and compare details.

Peter

--
Title: ProPhotoRGB
Post by: Ray on August 18, 2005, 11:23:02 am
Well, that's killed the thread, hasn't it! We're all in agreement  :D .
Title: ProPhotoRGB
Post by: digitaldog on August 04, 2005, 09:26:16 am
Quote
The only con to ProPhoto is a slightly greater chance of posterization or banding if editing in 8-bit mode. But if you use 16-bit mode (which you should be doing anyway) this is irrelevant and there is no real downside to ProPhoto.
The “downside” is a heck of a lot of potential colors you can’t see. You might be editing colors out of display gamut that fall within working space gamut. For 99% of users out there, this is the case with Adobe RGB (1998) as ProPhoto RGB. Unless you have one of the new Adobe RGB (1998) gamut sized display that is. This is a minor issue but one users should be aware of. I’d rather have the colors at my disposal and be very careful about editing extreme saturated colors (IF they happen to be in the image) then not have them to begin with.
Title: ProPhotoRGB
Post by: Ray on August 05, 2005, 12:06:34 pm
Quote
As for the idea of a wider space only being useful for very saturated colors, there’s more to it than that.
My non-technical understanding would be, if I have a pure, saturated yellow paint in my pallette, then I can mix it with other colors to produce shades that I couldn't get if my yellowest yellow was not pure, say slightly green or blue.

I've just tried a little experiment setting 'proof setup' to a Bill Atkinson Premium Gloss profile for the Epson 9600. My eyes have already told me I will get a purer yellow on this paper using ProPhoto, so I was curious to see what the numbers are.

For pure RGB yellow (255,255,0) ARGB is within gamut for this paper at maximum saturation, ie. it's not possible to make it out of gamut. However, using ProPhoto the saturation has to be brought back a small degree (-6) with the hue/sat control in PS. The proof RGB numbers, second reading on the info pallette, are 254,255,28 for ProPhoto and 242,255,81 for ARGB. The numbers tell me the ARGB yellow at maximum saturation has more blue and green, and that's what I see on the paper.

However, all the other primary colors at maximum saturation are out of gamut by a significant degree for both color spaces in relation to this glossy paper, particularly green and cyan which have to be brought back by 62 points on the hue/sat control in the case of ProPhoto and 47 and 29 points respectively in the case of ARGB.
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 05:31:00 pm
Quote
Quote
First, with rendering intents to output spaces, you have to decide if you’ll clip the colors or compress them. ...
Just a friendly question:

Are there any printer profiles
which support Perceptual rendering in way
which assumes that the source space was ProPhotoRGB?

Peter

--
No. Output profiles don’t have any idea when built what the source color space will be.
Title: ProPhotoRGB
Post by: Mark D Segal on August 06, 2005, 10:23:20 pm
Ray, my understanding of how all that you just mentioned works, in a nutshell, is as follows. D50 and D65 are two conventions for the color temperature of the monitor, and the color management folks tell us if we use 6500K on the monitor in our minds eye the image looks closer to a daylight reflected image than it would if we used 5000K monitor temperature, eventhough daylight lamps are in the range of 4800-5000K. When you ask them why, they just tell you it is observed experience about how we humans function (whoever said coherence and consistency were hallmarks of the human condition?).

The main parameters for calibrating a monitor are the white point, black point and gamma. Once these are set, profiling is done to measure the numerical differences between the (correct) data describing the color reference patches of the profiling software and the (perhaps incorrect) values the monitor shows them as. These measurements are then used to create a profile that neutralizes these differences so the monitor shows the colors of the file data. Likewise the printer profile measures and neutralizes differences between the (correct) data in the software file for each patch on the profiling target and the (perhaps incorrect) numerical values the printer prints them at. (Both sets of profiles calculate interpolations for all the data between these reference points.)

The file data is "nerve central". Once these two profiles are in place, the system is color managed because both the monitor and the printer are being managed by the two profiles to reproduce the same set of numbers in the file. All file data that is in gamut for both the monitor and the printer/paper should look pretty much the same, allowing for the fact that transmitted and reflected light are inherently different. We cannot see on the monitor colors that are out of the monitor's gamut. As there is no reason for the monitor gamut and the printer/paper gamut to be the same, Photoshop's soft-proofing module simulates an impression on the monitor of what the printed image will look like once we activate it with the printer profile that will be used for printing. Note, we are not profiling the monitor with the paper profile. Photoshop just uses the paper profile to create the soft-proof.

As far as I have been able to parse it, this whole discussion about whether or not it is useful to work in ProPhoto color space so far boils down to two propositions: (a) if Prophoto includes - but ARGB98 excludes - values that current and future generations of printers can reproduce, we should retain those values because they will improve printed image quality; ( as long as we work with 16 bit data, there is very little risk that Photoshop's shakedown of out of (printer) gamut colors will produce any noticeable banding.
Title: ProPhotoRGB
Post by: paulbk on August 05, 2005, 10:06:19 pm
Aside: “using Soft Proofing correctly, you can be about 90% accurate in your visual predictions on-screen to print.”
As I said, using a large color space puts the fun and intrigue back in printing.

Seen from a different point of view: If you send the same file to the printer you get the same print every time. Even if half the pixels are out of print space gamut. The print process is deterministic going one way. But the reverse is not true. If you could run time backwards and feed the same print into the printer you will not get the same file every time. Because there is only one in gamut file and many many out of gamut files that will render to the same print.
True?
Title: ProPhotoRGB
Post by: PeterLange on August 07, 2005, 05:22:52 pm
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Peter, I don't think that is correct. Firstly we are not converting a color space to a printer profile. As I mentioned above the printer profile measures and corrects differences between the file data and how the printer reproduces that data.

Mark,

I’m not sure if I get your point.

RelCol is always RelCol (afaik).  All in-gamut colors remain unchanged, whereas all out-of-gamut colors are mapped to the surface of the target space.  The more you have, the more it leads to an overpopulation = posterization = loss of details (also called clipping which may be a little bit misleading).

Peter

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Title: ProPhotoRGB
Post by: Mark D Segal on August 08, 2005, 08:35:33 am
My thinking exactly. Some of this stuff can be in the realm of angels dancing on the head of a pin; that said, it's still fun being just geeky enough to get under the hood and better understand some basic principles at play.

By the way, about a year ago I also tried alternative rendering intents on a photo of some buildings and trees taken in downtown Grenoble, France. Using my Epson 4000, Enhanced Matte paper and Epson's profile, I DID see subtle differences in some of the shades of green, sky hue and colours of the walls - but I emhasize the differences were subtle and most noticeable with Absolute Colorimetric; this was to be expected (Real World Color Management, page 92).
Title: ProPhotoRGB
Post by: Mark D Segal on August 09, 2005, 04:32:13 pm
Andrew, what I take from your nuanced response is that there is a (perhaps very) low probability risk of encountering some "issues" (whatever those are) in normal photographs using ProPhoto colour space, but - going back to earlier posts - perhaps this risk is worth taking, because we know that some of today's printers can reproduce some colour values that ProPhoto retains but ARGB98 does not and this is likely to become more pronounced with future improvement in printer technology. Would this be a reasonable way of drawing together the key implications of this whole discussion?
Title: ProPhotoRGB
Post by: Ray on August 12, 2005, 12:42:52 am
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Insure the output profile is accurate, especially with respect to the soft proof table (the table in the profile that controls the soft proof, not the actual output)

Andrew,
I don't have the equipment to make my own profiles. The profiles I used with my Epson 1290 are Pantone created profiles freely available for various Epson papers and recommended as being quite satisfactory by Ian Lyons.

Now I know they are not going to be the best. There's variation amongst desktop printers, just as there is with lenses of the same model. But I found these profiles to be good enough at the time. I now use an Epson 7600 for critical work.

The example I've been using to make a point about the gamut warning function is probably less relevant with modern papers, inks and profiles which probably all have fairly close gamuts. For example, with a saturated image open on screen, gamut and proof colors ticked, black point compensation and 'simulate paper white' ticked in custom proof setup, one can switch between the various profiles that are in one's color folder and observe the effect any particular profile has on those ugly gray patches.

For example, I've got an image in PS at the moment I've been workin on. I've increased the saturation a lot because I like saturated colors. With Epson's 7600 Watercolor profile (device to simulate) there's a moderate degree of gray patches; with Textured Fine Art paper there's a very slight degree of gray patches; with Premium Lustre there are no gray patches whatsoever. However, with the Pantone/Epson PhotoPaper profile, virtually half the image is covered in gray patches. Photopaper is an old paper type. It doesn't appear to have nearly as wide a gamut as Epson Premium Gloss and from past experience, if I were to print this image on Photopaper and let the rendering intent sort things out, then shadow detail would be severly compromised in a way that is not visible on my calibrated monitor in proof setup.

I've assumed all along that the gamut warning is giving me a fairly accurate indication of the comparative size of the gamut of any particular paper type. But if you're saying this gamut warning in PS is basically a useless piece of crap, then I'm natuarally wondering what tool could replace it  :D .
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 01:57:15 pm
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“..if your original capture does not contain tones out of the gamut of AdobeRGB, then there is no point whatsoever (and quite a few negatives) in using ProPhoto as your color space unless you plan to artificially manipulate the saturation of your image to a considerable degree.”

I’ll go one step further, and I know nothing about color management. You don’t have to be a color scientist to understand this: If you are working in a color space you can’t print, you are doing a blind edit. That’s a fact on it’s face. The rest is a matter of degree.

What’s amusing are those who say they are preserving colors by working ProPhoto even though they know they can’t print the colors they are “preserving.” And worse, they can’t even see some of the colors they are preserving. It boggles.

Working in 16 bit is an entirely separate issue.
If you’re shooting RAW to some color space on the fly, you can’t know what scene may or may not contain data beyond Adobe RGB (1998). IF you’re shooting RAW, you can select, as I do when viewing the ACR histogram. No harm done.

As for the gamut of the printer, what printer and when? If you look at the gamut of printers in the last 10 years (a century in dog and digital years), a lot has changed. I have no idea the what I may be able to print with a 12 color ink jet or some other technology in 5 years or less. As such, I find no reason why I should funnel color I can capture into a smaller space based on what I may be able to reproduce today. If 100% of my work went out to a four color press, this would be a moot point. I’ve got right now, a Pictrography 4500, Epson 2400, 2200, 980 and R800. I have no idea what I’ll be using next year, let alone 10. There’s no harm at all in using a wider gamut container (editing space) in 16-bit considering my crystal ball isn’t always working with respect to future output technology.

There’s no output device that can print sRGB other than a display. So the argument that there’s no device that can output ProPhoto RGB isn’t compelling. Working space are not output spaces and vise versa.

16-bit isn’t an entirely separate issue since the bottom line here is what data can you capture and keep and what should you keep?
Title: ProPhotoRGB
Post by: paulbk on August 05, 2005, 03:53:57 pm
There is nothing said thus far to refute the premise of Jeremy Daalder's article. This is not about opinion. It’s about numbers. Predictable, deterministic math. It all boils down to a squirt of ink determined by a number. It’s as simple as that.

I’m not saying don’t use PhoPhoto. Use it. Have a ball. I am saying that when your working space is far greater than your printer/paper space you are knowingly introducing an unnecessary unknown. Which adds mystery to the output but nothing else of value.

If some one can explain how a color outside the print space is of some value during editing, I’ll read it. But at the moment, it’s mere religion.
Title: ProPhotoRGB
Post by: Ray on August 05, 2005, 09:06:05 pm
I see no one has answered my question regarding the actual average range of discrete colors in a 24 bit 1Ds image. I thought it might help to get in perspective concerns that some have about ProPhoto and 8 bit. There are programs for calculating the actual numbers of different colors in any given image. I vaguely recall someone with the British Journal of Photography once used such a program on a selection of images and found the numbers surprisingly small, like 500 to a few thousand.

Despite using ProPhoto myself for all the reasons outlined in this thread, I've never done any rigorous comparison of a selection of real world images, editied in both ARGB and ProPhoto before printing. Ultimately, the proof of the pudding is in the eating. I suppose I wouldn't expect to see any significant difference in the results unless I knew precisely where to look, or how to select  images that could reveal the differences.

For example, if I wanted to demonstrate the differences between sRGB and ARGB, I would choose an image with lots of solid green, the green of leguminous plants and freshly fertilised lawns, and lots of subtle shades of cyan. I would expect, no matter how hard I tried, I would not be able to get a green, green enough with sRGB (too much yellow), and some of the subtle and distinct shades of cyan would merge, compared with the ARGB rendition.

To demonstrate the differences between ProPhoto and ARGB, the obvious choice of image would be one with bright yellow flowers as well as canaries, but also subtle shades of dark brown, (and what else? I'm not sure.) It should be possible to produce an image containing a series of dark tones that are distinct when printed from the ProPhoto color space, but not distinct (merged) when printed from ARGB.
Title: ProPhotoRGB
Post by: Schewe on August 07, 2005, 12:40:12 pm
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In workflow A camera colors are clipped in 2 steps, in workflow B in one step.

Exactly. . .in 'A' you clip the color before even bringing it into Photoshop-thereby forever giving up the possiblitity of using the color data that get's clipped. In 'B' YOU have control over what does and doesn't get clipped and how it gets clipped...so, the question is, do you want to have control? Or, do you want to toss camera colors before you even get the image into Photoshop?

Me? I'm a control freak-I want total control. I don't want color that the camera can capture to be clipped merely because the working space can't contain it.

sRGB clips a lot...
Adobe RGB clips a little...
Pro Photo RGB doesn't clip...

What you do with your image is up to you, but personally, I don't want to lose anything. That's why I use 16 bit and Pro Photo RGB.

Don't Fence Me In...pretty much says it all. Adobe RGB is a fence that reduces what the camera can capture. I think the grass is always greener on the other side-and in the case of Pro Photo RGB, that is exactly the case!

:~)
Title: ProPhotoRGB
Post by: PeterLange on August 07, 2005, 05:46:07 pm
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Me? I'm a control freak-I want total control. I don't want color that the camera can capture to be clipped merely because the working space can't contain it.
Jeff, thanks a lot for explaining the philosophy.

Peter

P.S.: I have no luck with the Color Range “Out Of Gamut” option.  Selection always differs from the SoftProof / out-of-gamut marks.

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Title: ProPhotoRGB
Post by: digitaldog on August 09, 2005, 12:23:29 pm
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The Granger Rainbow is certainly brighter and more colourful when assigned a ProPhoto profile (as opposed to sRGB and ARGB) both before and after proof setup for Premium Glossy, RelCol, simulate paper white and  sat reduction to tame gamut.
Brighter appearing when you Assign or after you’ve output the file?

Brighter appearing due to the new meaning of the numbers certainly makes sence. But the numbers haven’t changed (only the definition). This is where this exercise is interesting. Let’s distill the Granger Rainbow down to a single pixel, say R255/G0/B0. You’ve built this one pixel (and in fact the entire Granger Rainbow) but it has no specific color space associated until you assign a profile. If you assign sRGB, the number is still R255. If you assign ProPhoto RGB, well the number is still R255. The only difference is you tell the color management system the scale of the R255.

So we take three identical files, all filled with R255 but define where in the color space that most saturated red lives within context of human vision. That info is used when we convert to an output color space. The new number will be different for each of the three files (sRGB, Adobe RGB (1998) and ProPhoto). We’ve used the same output profile, the same rendering intent and the same original R255 value. This little tests is useful in showing the effect of the source definition of the color space. It’s interesting when using the same output profile for the same device but built by differing packages (especially with Perceptual rendering).
Title: ProPhotoRGB
Post by: digitaldog on August 09, 2005, 04:41:16 pm
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The Raw file was processed at camera-default settings to ProPhotoRGB, 16 bit.
And that alone could be a major factor in how well or poor your results are with no bearing on any color space you converted the file into.
Title: ProPhotoRGB
Post by: Ray on August 17, 2005, 10:10:24 am
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NO image could contain that color. Even if it could, we could see a tiny fraction of those colors (we can’t even see anything close to 16 million color simultaneously). This is all math being used to define a possible but unfortunately impossible human experience. Don’t forget, there’s math that says a bumblebee can’t fly.
I wouldn't argue with that. I suspect many of our images have no more than a few thousand discrete colors. But whether an image has 50 colors or 1,000, I don't believe the number of colors increases by moving to a larger color space.
Title: ProPhotoRGB
Post by: paulbk on August 05, 2005, 01:47:54 pm
There is nothing to debate here. It’s a closed question. The J. Daalder article is air tight. To whit:
“..if your original capture does not contain tones out of the gamut of AdobeRGB, then there is no point whatsoever (and quite a few negatives) in using ProPhoto as your color space unless you plan to artificially manipulate the saturation of your image to a considerable degree.”

I’ll go one step further, and I know nothing about color management. You don’t have to be a color scientist to understand this: If you are working in a color space you can’t print, you are doing a blind edit. That’s a fact on it’s face. The rest is a matter of degree. Working in ProPhoto it's a large degree.

What’s amusing are those who say they are preserving colors by working in ProPhoto even though they know they can’t print the colors they are “preserving.” This from the folks who say calibrate your monitor and work in a color managed environment so what you see is what you get. Well if you’re working in a color space that’s five times the size of your print space, then what you see is what you see. And any relationship between what you see and your print is good fortune.
It boggles. But if it makes you feel good, I say, enjoy! Life is too short. Where's Didger when you need him? I miss him.

Working in 16 bit is an entirely separate issue.
Title: ProPhotoRGB
Post by: digitaldog on August 05, 2005, 04:04:36 pm
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There is nothing said thus far to refute the premise of Jeremy Daalder's article. This is not about opinion. It’s about numbers. Predictable, deterministic math. It all boils down to a squirt of ink determined by a number. It’s as simple as that.

I’m not saying don’t use PhoPhoto. Use it. Have a ball. I am saying that when your working space is far greater than your printer/paper space you are knowingly introducing an unnecessary unknown. Which adds mystery to the output but nothing else of value.

If some one can explain how a color outside the print space is of some value during editing, I’ll read it. But at the moment, it’s mere religion.
Which squirt of ink and when?

The reason the working space is so much wider than the output space in many areas is it has to be. Read what Bruce wrote so clearly.

There are NO perfect working space or we’d only have one.

Trying to make a perfect fit of working space to output space (even if you only defined one printer) would be nearly impossible. Working spaces are based on synthetic color spaces that mimic displays more or less. Output devices have vastly different shaped gamuts. So for those that want to fit as much if not all the output space in the working space, you need a pretty big honking working space. So some colors WILL fall outside output gamut. That’s just a fact of life. You’re trying to fit a round peg in a square hole. The square hole has to be big enough to fit the round peg and yes, there are areas as a result that fall way outside the round peg. And that’s a problem why?

Of all the well known and designed wide gamut RGB working spaces, ProPhoto RGB has proven over the years to handle the task of a wide gamut working space. You either want to contain all the colors you capture (and maybe, hopefully reproduce them) or you don’t. It’s pretty darn easy to see if, when you’re in ACR, the scene falls within or outside of a working space like Adobe RGB (1998). IF you care about those colors, you’re far better off using a big honking space like ProPhoto RGB or you decide you don’t care about those colors. Use sRGB, use ColorMatch RGB, use whatever.

There’s far less problems gathering the color you captured in high bit in a big space than tossing the colors for a smaller space for lots of users (who care about getting all the colors they could capture). Again, you either care or you don’t. If you care, your only real option is to use a big honking color space.

There is no unnecessary unknown. There IS a big unnecessary unknown when you clip colors, namely what colors did I just throw away and what device (and when) could I have used them. Once gone, they are gone forever. I don’t see that as being a compelling reason to use a smaller working space but maybe you do.
Title: ProPhotoRGB
Post by: Jack Flesher on August 05, 2005, 07:51:32 pm
Jeff:

So very well said -- my compliments

I can only add emphasis to your gamut comments on the new K3 (4800) inks versus the older Ultrachrome (4000) inks.

That and the fact that my monitor is clearly the limiting factor in my digital imaging workflow at present.

Regards,
Title: ProPhotoRGB
Post by: Schewe on August 07, 2005, 12:32:29 pm
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The Color Range tool offers an option to select “Out Of Gamut” colors.  Which target profile does it refer to?  It seems that the selection differs considerably from the SoftProof / out-of-gamut marks.

The Out of Gamut warnings and Color Range selections refer to whatever is the current soft proof set up. If there is no soft proof set up on, then it's the "default" set up which, unless changed, is your current CMYK profile. You can change the default by, with no image open, changing your soft proof setup to something else, such as your main Epson profile, a different CMYK, etc.

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After you’ve processed a file through Camera Raw (ProPhotoRGB, 16 bit), do you instantly enable the SoftProof to the printer/media profile, or is there an editing step in-between based on “normal” presentation on screen?

Depends-if I'm planing of taking the image directly to print, then I turn on softproofing first thing. All of my post Camera Raw tone & color corrections need to be done in "light" of the final print output. I usually turn off softproofing when just retouching.

However, if the plan is to have my converted raw file opened as a PP RGB and my plan is to just produce a master file for later use in either print, web ot whatever, then I just work along with softproofing off. Later, if I need to make a print, I turn softproofing on for checking before print.

Also, and this may surprise some, I'll also use softproofing when trying to determine optimal image sharpening-since the nature of the reduced dynamic range of the final print can have an effect on the required sharpening. Note: PhotoKit Sharpener already takes the final output into consideration when you use the Output Sharpening. That's a "product feature" we built in. But I will use softproofing to view the image for the purpose of creative sharpening.

Softproofing is _NOT_ just "all about color" it's all about what the image will look like when ink hits paper...the more you can do to prepare the image for the appearence of the image on paper, the less time you'll spend tweaking print setting, pritning a test and further tweaking.

Ink and paper are expensive enough that you can save both considerable time and money by accurate predictive image eval prior to printing. There really shouldn't be a lot of surprises when the print comes out of the printer, regardless of the working space you choose.
Title: ProPhotoRGB
Post by: Mark D Segal on August 07, 2005, 06:07:01 pm
Peter,

Here is what Relative Colorimetric rendering intent does, according to "Real World Color Management" 2003 Edition page 89:

".......It maps white in the source to white in the destination, so that white on output is the white of the paper rather than the white of the source space. It then reproduces all the in-gamut colors exactly and clips out-of-gamut colors to the closest reproducible hue. ........"

Now, if that is what it does, it is by no means obvious to me how variations in the extent of out-of-gamut colors being remapped (as you move from ARGB98 to Prophoto, e.g.) could have a differential visible impact on posterization of actual photographs.
Title: ProPhotoRGB
Post by: Ray on August 09, 2005, 12:16:01 pm
The Granger Rainbow is certainly brighter and more colourful when assigned a ProPhoto profile (as opposed to sRGB and ARGB) both before and after proof setup for Premium Glossy, RelCol, simulate paper white and  sat reduction to tame gamut.

I'm not at my printer at present, but I have no doubt which would look the best if I printed all three images on my 7600.

One thing that puzzles me, however. To bring these 3 images within the gamut of the Premium Gloss profile requires a greater reduction of saturation (with the hue/sat tool) for the ARGB and sRGB images than for the ProPhoto image. (ARGB -71; sRGB -68; PP -62.) Does this seem right?
Title: ProPhotoRGB
Post by: digitaldog on August 17, 2005, 10:08:03 am
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I just can't understand that statement. I have an sRGB 24 bit 50MB image that contains every combination of the 255 levels of red, green and blue; ie 16.7 million colours, each pixel representing a different colour. (Give or take a few hundred or thousand, Jani   ).

I convert the image to the bigger ProPhoto color space. I've still got 16.7 million colors. If I were to get more, the file size would have to increase. I've never noticed that happen, have you?

If I say the colors have changed in character; that some of them are more saturated than they were in the sRGB space, then that is a different statement to saying I have more colors. Let's try to be logical here. More colors does not mean more color, if English is your first language. If you think it does, then thats the source of the confusion. By 'more colors', I mean 'a greater number of discrete shades of color'.
The scale is totally different. R255 in sRGB isn’t the same color as R255 in ProPhoto RGB. The R255R in ProPhoto is much more saturated. It’s not the same color but has the same number.

Now if you want to debate that the max red in one color space which is more saturated than another isn’t really “more colors”, OK.
Title: ProPhotoRGB
Post by: digitaldog on August 09, 2005, 04:39:02 pm
It’s pretty simple. You have a capture device and scene gamut that falls outside of Adobe RGB (1998). You have output devices who’s gamuts fall outside Adobe RGB (1998) such as my Epson 2400. Your goal is to capture and reproduce all the colors you can. Adobe RGB (1998) is fine but not up to that task, ProPhoto RGB is.

As I’ve said so many times, there is no such thing as a prefect RGB working space. But you could substitute working space in that sentence with just about anything we work with in Photography and imaging.
Title: ProPhotoRGB
Post by: Ben Rubinstein on August 05, 2005, 09:40:24 am
Correct me  if I'm wrong, and I think that this is what Paul has been saying all along. If my prints are made on a Fuji Frontier which prints to the sRGB colour space, then does it not make more sense to work in that colour space  from the beginning of my workflow so that I am not assuming certain saturated colours are contained in ACR using prophoto and then converting to the print colour space of sRGB just before sending to print, losing the saturated detail and having to start again.
Isn't the point of WYSIWYG to be just that? What's the point in working with a wider gamut throughout the workflow if you aren't going to use it for print, you will just be getting yourself in trouble.
Of course this is an extreme example of a printer with a limited colour space. However even though prophoto may give an advantage for certain colours on certain printers, would it not be better to work with a colour space throughout the workflow that is completely contained within the printers ability, such as Adobe '98, so at least you know exactly how the colours are going to come out in print from start to finish?
Title: ProPhotoRGB
Post by: Schewe on August 05, 2005, 07:30:53 pm
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I’m not saying don’t use PhoPhoto. Use it. Have a ball. I am saying that when your working space is far greater than your printer/paper space you are knowingly introducing an unnecessary unknown. Which adds mystery to the output but nothing else of value.

If some one can explain how a color outside the print space is of some value during editing, I’ll read it. But at the moment, it’s mere religion.

It's neither a religion nor an unknown-even if _YOU_  don't yet know how to do it.

Look, you have a capture space, a working space and a printer space. To take a capture space and by virtue of converting to a working space, clip or throw away color, you've forever limited the usability of such color and lessened the value of the image for the future.

Going from ProPhoto RGB, which contains not just "most" of the colors cameras can capture, but _ALL_ colors a camera can capture, to your output profile allows _YOU_ to decide how the color transforms will be handled.

It's _NOT_ religion that today's inkjet printers can use a meaningful amount of color outside of even Adobe RGB, and it ain't just Canary yellow but in the case of the new K3 inks a LOT of dark deep saturated colors that fall outside of Adobe RGB, but within ProPhoto RGB _AND_ the K3 ink gamut.

Color outside the print gamut itself can be useful in that YOU can control how those colors are remapped. How? Photoshop Soft Proofing-if you know how to use it. The Absolute Colormetric use of Soft Proofing (using ink black and paper white) can show you exactly how to adjust what are out of gamut color into the gamut of the output device. You can alter the relationships of the colors and actual produce results by virtue of those out of gamut colors. Yes, they won't "print" but they will absolutely impact how the final output looks. Yes, today's displays can't show you "everything" but using Soft Proofing correctly, you can be about 90% accurate in your visual predictions on-screen to print.

If you don't have the data, you can't do anything with the data...hense the reason for working with data outside of the color space of the output and if you know what you are doing, working with data outside the color space of your monitor.

Personally, with the recent rate of progress in cameras, output devices and displays, if you _DON'T_ work now with an eye to the future, you are being incredibly short sighted. Michael's review of the 4800 not withstanding, the total volume of color capable of being reproduced by the 4800 vs the 4000 is seriously larger-even if he didn't do the volume mapping to prove it to himself.

We'll have computer displays very shortly that will have at least if not larger color gamuts than Adobe RGB and luminance output that is bright enough to work in normal room light.

To be honest, even ProPhoto RGB is actually too small a color space to work in when limited by 16 bit. With the deployment of even limited HDR space in Photoshop CS2, we're looking well beyond the current limitation of 16 bit integer to 32 bit floating point and new color spaces that will extend even beyond what ProPhoto RGB can contain.

Will we see cameras that can capture or printers that can print it? Not for a while yet, but remember, image processing is also an advancing art and still limited to the current algorithms in use-which keep getting better. But even if you can't capture or print the colors, you CAN archive them in your files for a time in the future when you may be able to. Also, understand that image processing is just really elaborate math-and the more data you have, the more refined and accurate the results of your processing algorithms. Which translates to better results even in smaller gamut output.

There are a lot of people out there with a little bit of knowledge and often the "nearly blind" will end up leading the "blind". The "unknown" won't stay that way long, and there's little value in "religion" as you term it...but there is science, if you are inclined to learn it.
Title: ProPhotoRGB
Post by: Hermie on August 05, 2005, 02:21:21 pm
By the way, does anyone of you use

- basICColor display profiles (gamut-compressed profiles, which reasonably simulate colors outside the monitor gamut) or
- Photoshop's "Desaturate Monitor Colors" control

in relation to ProPhoto workflow?

Herman
Title: ProPhotoRGB
Post by: paulbk on August 05, 2005, 04:29:03 pm
You realize that when a photo file color doesn’t map into your print space the rendering process does it for you. In other words, what you see is NOT what you get. You get whatever the rendering process gives you. That’s why in 2005 we still hover over the printer with a fair bit of apprehension to see what it will hatch. We don’t do that with text printers any more because technology has taken the mystery out of it. Back in the DOS days of 6 pin dot-matrix printers it wasn’t so deterministic. Some day fine art printing will be as deterministic as laser jet text is today. But it won’t be tomorrow.
Title: ProPhotoRGB
Post by: digitaldog on August 08, 2005, 10:17:01 pm
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Andrew's response to Ray to-day is very sensible, but it deals with varying impacts of different rendering intents, whereas the issue at stake in this discussion thread is whether there is a differentially worse impact from the use of whatever rendering intent when the working space is Prophoto rather than ARGB98.
Actually if you’re referring to the use of a Granger Rainbow to see the effects of a conversion, the source profile used is going to be part of the evaluation. That is, Assign sRGB, Adobe RGB (1998) and ProPhoto to the same numbers and convert using the same output profile and rendering intent. You’ll see some very interesting results!
Title: ProPhotoRGB
Post by: Ray on August 09, 2005, 09:26:11 pm
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Brighter appearing when you Assign or after you’ve output the file?
Brighter (more saturated, or perhaps more intense is the right word) on screen immediately after assigning the 3 profiles, but also after applying proof setup/simulater paper white etc and reducing gamut for all 3. The sRGB and ARGB rainbows are dowdy by comparison.

If the numbers are the same, it would seem the reason why the ProPhoto image did not require the same degree of desaturation as the ARGB image (to bring them both within gamut) is a result of the Premium Glossy paper's capacity to handle at least some of the greater saturation of ProPhoto. Does that make sense?

The surprise is, the sRGB image required less desaturation to bring it within gamut than did ARGB. It would make more sense if this was the other way round.
Title: ProPhotoRGB
Post by: PeterLange on August 07, 2005, 07:13:11 pm
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Mark,

I do not see any contradiction, unless you seriously suggest to map an out-of-gamut color onto an in-gamut color.

With RelCol, out-of-gamut colors are simply clipped to the nearest color in CIE Lab. In detail, an out-of-gamut color is moved along a line of constant Lab hue angle – until it reaches the border of the target space.

At page 71 of your book it is explained that such moves are not perfectly in line with the perceived hue.

Peter

--
Title: ProPhotoRGB
Post by: digitaldog on August 10, 2005, 12:38:26 pm
There are two options for viewing out of gamut colors under the View menu. One is to setup a soft proof using the output profile, rendering intent and options like Simulate paper/ink. This IS the way to be evaluating the soft proof/out of gamut colors.

The second, older and quite useless way is to pick “Gamut Warning” which places a gray (by default) mask over out of gamut colors based on what you’ve set in Proof Setup. The idea is to desaturate those areas so they fall into output gamut. This is a old, useless, time consuming and not very accurate way to be handling this process.