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Author Topic: sRGB, Adobe RGB, and ProPhoto RGB - Exploring the Gamut Limitations of Printing  (Read 21161 times)

Doug Gray

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No it's not. It's an RGB working space, a special group of synthetically defined color spaces based on three simple attributes: white point, chromaticity values and gamma (TRC). How can ProPhoto RGB be an output color space when it defines "colors" (device values) that are both invisible to us and are impossible to output to any device? All about RGB working space: http://www.adobe.com/digitalimag/pdfs/phscs2ip_colspace.pdf I don't again understand what you're saying.
Terminology varies. I do like your "working space" terminology. However, matrix based colorspaces are also referred to as output referred colorspaces. Sorry for leaving off the "referred."

See Jack Holm's (HP Principal Color Scientist) description of them:
http://www.color.org/documents/AdvColMgmt_for_DP.pdf



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There's no such provision in LR it's processing pipeline is always using ProPhoto RGB primaries and thus it's gamut. One can export to a smaller gamut color space in that product and that's useful when you need sRGB for the web or mobile devices. You can't print sRGB though LR, it's not possible. As Mark pointed out, it's always sending ProPhoto RGB gamut through it's print module. If you happen to have clipped all that nice wider gamut data and have sRGB rendered data, the damage is done. None the less, IF edits are applied to the rendered image, ProPhoto RGB is used on that clipped data. And raw data isn't clipped to sRGB thankfully.
This is exactly my point. Converting highly saturated images that exceed sRGB gamuts to sRGB for the Web can sometimes produce a much different image than the image that is printed using a large gamut space. Your Wide Gamut Test image is a case in point where when converted directly to sRGB messes up the image compared to what is printed. Sure the image is well outside sRGB and aRGB but that is no reason not to create an image when needed for the web that is highly distorted from what is printed.

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The web and thus sRGB are the lowest common denominator and it's kind of foolish to throw the baby out with the bath water when you intend to print that data too.
Couldn't agree more. The only point I'm making is that if you need to create an image for the web that is as close as possible to what you can print converting directly from a wide gamut space to sRGB is flawed when the starting image has many large areas of color far from the sRGB space.
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Doug Gray

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So the goal is to make the print as desaturated as an sRGB browser viewing that image on the web? Again, I don't see why one would do that.
Your technique isn't new and is useful for print in one case I can see; proofing (make my wider gamut Epson better match a contract proof).

The goal, quite simply, is when one has to have an image for the web and the source image is in a high gamut space, then this two step approach more accurately renders high saturation colors that are within sRGB. While sRGB is quite limited there is zero reason to distort colors more than is necessary and simply converting to sRGB, either in LR or PS from ProPhoto RGB is very suboptimal when the purpose is to produce an sRGB image that is as close as possible to the print image that contains colors outside of sRGB.
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Doug Gray

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I have to wonder if consumers, who appear to prefer 'saturated' colors will move to wider gamut displays as they become less expensive. If so, it will be interesting to see where sRGB goes in the future.
Good question. The progress to date has been slower than I anticipated.

My typical work is done in 16 bit ProPhoto.  Most of my output can be converted directly to sRGB if needed for some reason. The only time I use this two step process is when I need to create a universal web image that comes as close as possible to an image with highly saturated colors. It's actually rare unless I am dealing with synthetic images such as trying to create a nice rainbow effect that looks reasonably close when printed and viewed in sRGB.
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Doug Gray

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Over the last couple days I've been archiving a bunch of old photo albums, some with pictures that are almost 100 years old.  I set up the camera to shoot raw, with appropriate lighting at 45 degrees to each side. Shot a Colorchecker and created a profile for that illuminant that renders scene referenced images. The initial purpose being to capture accurately the album pages. From this I can print an image that exactly matches those the album, one of the few times Scene referred images and Absolute colorimetry is useful. It turned out the images are all within sRGB gamut so no back and forth is needed or useful. I can also share them on the web with my friend's family members who wish to have a nearly exact image of the albums.
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digitaldog

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Terminology varies. I do like your "working space" terminology. However, matrix based colorspaces are also referred to as output referred colorspaces. Sorry for leaving off the "referred."
The Output or 'referred' term per se isn't necessarily. The point is, RGB working space's are not output color spaces nor based on any output device other than a theoretical emissive display in a very fixed condition and environment.
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See Jack Holm's (HP Principal Color Scientist) description of them:
http://www.color.org/documents/AdvColMgmt_for_DP.pdf
Jack and I co-authored this for the ICC so I'm familiar with Jack and the terminology: http://www.color.org/ICC_white_paper_20_Digital_photography_color_management_basics.pdf
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This is exactly my point. Converting highly saturated images that exceed sRGB gamuts to sRGB for the Web can sometimes produce a much different image than the image that is printed using a large gamut space.
I'm far less concerned about posting images on the web than printing them! And it's not difficult IF necessary to edit images from a wider gamut to sRGB for the web. But in the end, it's a huge crap shoot anyway! How many people viewing all that hard work are viewing on calibrated displays (calibrated how to what goal?) and using color managed web browser?
It's a bit like worrying if the meat in a MacDonalds hamburger contains GMO's when it is filled with salmonella. The web and sRGB are the lowest common denominator. I'm not going to hose my files for any or all output because I need a tiny, low resolution JPEG for posting on the internet.

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Your Wide Gamut Test image is a case in point where when converted directly to sRGB messes up the image compared to what is printed. Sure the image is well outside sRGB and aRGB but that is no reason not to create an image when needed for the web that is highly distorted from what is printed.
I can do that too. I simply do not understand the workflow you propose. I have the raw image data that produced those images in the Gamut Test File. Encode in ProPhoto RGB or sRGB? I need to make a print and maybe upload to the web. One encoding gives the data a permanent sex change operation and produces an inferior print. WHY would I do that?
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The only point I'm making is that if you need to create an image for the web that is as close as possible to what you can print converting directly from a wide gamut space to sRGB is flawed when the starting image has many large areas of color far from the sRGB space.
Every output device is different! Every display too. I don't see how or why I need to target a print, who's gamut is hugely larger than an sRGB display viewing a web image to match. And match on ONE display at that.
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Mark D Segal

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Here's the actual conversions done that demonstrates why the two step process is better when converting an image from ProPhoto to sRGB when trying to match a print made directly from Andrew's Printer Gamt Test File.

Focusing in on the Green, vertical gradient column locate a point equidistant from the bottom and left/right sides (a good location to take a verifying reading with a spectro) the ProPhoto RGB values are (7,255,7).  This is, of course, an unrealizable color that can be thought of as an intense, supersaturated green. This is not even close to being reproducible in sRGB, aRGB, a print gamut, or anything in our reality.

Let's follow the two paths of color conversion.

The first is straightforward. Convert the color to sRGB then print it using either Perceptual or Relative colorimetry. Let's use Relative for simplicity noting that we could instead use Perceptual. The results in sRGB are (0,255,0) over the entire bottom third of the vertical green column. So the conversion results in clipping. Let's look at the details. PP(7,255,7) is, in XYZ (PCS working space for matrix profiles) is 13.6, 71.2, .128.  Running the matrix conversion to sRGB and scaling to sRGB's almost 2.2 gamma yields  sRGB(-221, 279, -108). Since us mortals, and Adobe, can't deal with RGB values beyond [0:255] they are simply clipped to sRGB(0,255,0). That's a big haircut.  But does that get us close to the printer's gamut? No, it does not. Virtually all colors near sRGB's three primaries cannot be printed. Printer gamuts exceed sRGB and aRGB only along the gamut triangle's sides.

So what happens when we print sRGB(0,255,0) and compare that to printing the ppRGB(7,255,7). First the sRGB(0,255,0) is converted to PCS (Lab) then the Lab values, adapted for BPC, use the 3D LUTs to interpolate a set of RGB values to send to the printer. This process is a function of the printer profile so YMWV. Often, printer profiles simply map out of gamut colors to the closest color on the gamut boundary.

Using my printer and profiles (a custom profile with Epson PPG printed on a Canon 9500 II) RC w BPC resulted in a Lab value of 72,-53, 67 as read by a spectro.

Now let's examine what happens when the image is printed from ProPhoto directly to the printer using RC w BPC. First the ppRGB(7,255,7) is converted to PCS (Lab clipped [-128:127]) then the BPC adapted 3D lookup is output to the printer and the image is printed. On my printer this produces a Lab value of (60, -67, 56) which is very far off (Deltas E:21) from the yellowish green printed by converting first to sRGB.

By going through the convert to printer then convert back to sRGB allows one to more closely match the printer's actual image as printed from RAW or ProPhoto RGB to an image intended for the web.

The problem's encountered in this is loss of accuracy due to inaccuracies in the printer's BtoA->AtoB. Each transition can be expected to introduce error ranging from tenths of a DeltaE to several DeltaEs at the gamut boundary. So, unless an image is significantly out of aRGB or sRGB, I don't recommend this. However, it's great for images with a lot of synthetic colors such as rainbow or the grainger color gradients. It's not accurate per se since the colors are out of gamut, but it does make for a much closer match between a print image and an image in sRGB intended for the web.

Doug,

I'm having two problems: firstly, going back to post #2, there is no viewable image file by which to see what you are getting at. Secondly, I just loaded my widest gamut printer profile (Epson 4900 printing on Ilford Gold Fibre Silk, gamut volume of 977,000, let us call it "IGFS/4900" space) into a three-dimensional representation in CTP along with the OSX System profile for sRGB and examined them. What I see - very unambiguously, not even marginal, is that the two gamut shapes are very different, such that in some areas sRGB>IGFS/4900 and in others IGFS/4900>sRGB. (Please refer to the screen grab image, wherein green is the printer profile and red is sRGB.) Quite apart from the fact that the sRGB gamut volume is smaller at 832,478, in this comparison I suspect for purposes of your approach, the relative shapes are more determinative of outcomes than the relative volumes. Hence I would expect that if I implement your intermediate step of converting from ProPhoto to the IGFS/4900, and assuming the photo contains colours exceeding both the IGFS/4900 and  sRGB gamuts, I shed all the data occupying the space from from ProPhoto to IGFS/4900, implying that because IGFS/4900 < sRGB space IN SOME PARTS OF THE GAMUT, I have shed data - through the end of the workflow -  that would have been retained in a straight conversion from ProPhoto to sRGB that didn't first pass through the IGFS/4900 space. So I am still puzzled about the theoretical basis of the proposed alternative workflow.
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Doug Gray

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First, let me repeat I am totally with Andrew about not using sRGB or any smaller working gamuts than can be printed. This was an experiment to see how close one can come to representing an image in sRGB which bears the closest resemblance to a full gamut print. For instance to supply catalog images.

If anyone's interested, I can supply the matlab source code that runs this.

The image is from Andrew Rodney's printer gamut/profile test program available on his site. It consists of many highly colorful components some of which are in the full RGB space of ProPhoto. He calls it the "Printer Gamut Test File." It's particularly useful to see how out of gamut colors get printed and allows you to examine how profiles handle these colors. Some canned profiles are seriously flawed.

Attached is three images and a black and white image of the relative DeltaE in each location in the image. For these, black means DeltaE=0, White corresponds to DeltaE of 48 which occurs in locations where the ProPhoto pixel colors are extremely far from what can be rendered.

The average DeltaE was 4.3 for the modified approach (convert to printer, then sRGB) and 7.1 for the traditional approach of (convert to sRGB) before printing.



« Last Edit: December 04, 2015, 12:05:22 am by Doug Gray »
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Mark D Segal

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First, let me repeat I am totally with Andrew about not using sRGB or any smaller working gamuts than can be printed. This was an experiment to see how close one can come to representing an image in sRGB which bears the closest resemblance to a full gamut print. For instance to supply catalog images.

If anyone's interested, I can supply the matlab source code that runs this.

The image is from Andrew Rodney's printer gamut/profile test program available on his site. It consists of many highly colorful components some of which are in the full RGB space of ProPhoto. He calls it the "Printer Gamut Test File." It's particularly useful to see how out of gamut colors get printed and allows you to examine how profiles handle these colors. Some canned profiles are seriously flawed.

Attached is three images and a black and white image of the relative DeltaE in each location in the image. For these, black means DeltaE=0, White corresponds to DeltaE of 48 which occurs in locations where the ProPhoto pixel colors are extremely far from what can be rendered.

The average DeltaE was 4.3 for the modified approach (convert to printer, then sRGB) and 7.1 for the traditional approach of (convert to sRGB) before printing.

A dE measurement, as no doubt you know, needs to measure one thing versus another. Grateful if you would clarify exactly what two items of source information you are measuring, which when subtracted from each other (and using which dE calculation formula?) produce the dE?
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digitaldog

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A dE measurement, as no doubt you know, needs to measure one thing versus another.
Further, one sample versus the other. For more than one, we need a report like those from ColorThink Pro seen below, that provide an average and the number to produce the average is necessary and useful. For example, is 323 samples enough?
This also tells us nothing about color in context.

--------------------------------------------------

dE Report

Number of Samples: 323

Delta-E Formula dE2000

Overall - (323 colors)
--------------------------------------------------
Average dE:   2.90
    Max dE:   7.91
    Min dE:   0.00
 StdDev dE:   1.75


Best 90% - (290 colors)
--------------------------------------------------
Average dE:   2.53
    Max dE:   5.26
    Min dE:   0.00
 StdDev dE:   1.43


Worst 10% - (33 colors)
--------------------------------------------------
Average dE:   6.14
    Max dE:   7.91
    Min dE:   5.31
 StdDev dE:   0.65
--------------------------------------------------
Cross rendering from a larger gamut output to a smaller one isn't a new concept.

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Doug Gray

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A dE measurement, as no doubt you know, needs to measure one thing versus another. Grateful if you would clarify exactly what two items of source information you are measuring, which when subtracted from each other (and using which dE calculation formula?) produce the dE?
Standard Euclidean distance, CIE 1976 Delta E.
The references are the two images to the right compared to the first one which is the full print gamut.

I'm going to also produce a dE2000 histogram which is more uniform and will be more useful than the 10% - 90% reports that ColorThink reports produce per Andrew's request. Should post that shortly.
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Doug Gray

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As expected dE2000 numbers are much smaller for both conversions since more saturated colors tend to be harder to distinguish. More telling is both the smaller size of the histogram bins and smaller max dE2000. Roughly 50% of the pixels using the conventional conversion have a dE2000 above 1 while about 25% of the alternate conversion pixel dE2000's are above 1.

Fascinating stuff but not too surprising after I noticed that the standard matrix treatment going from large spaces to smaller ones is seriously flawed. People that make printer profiles can map out of gamut Lab colors to the nearest in gamut color thanks to the 3D LUTs.

Ideally, rather than converting directly to sRGB with the flawed and simplistic matrix math clipping I described earlier perhaps someone can create a standard 3D LUT profile for sRGB. It's might even provide better results and it would avoid the two step process of converting to the print profile then back to sRGB.

BTW, the "sample size" used is the entire image which contains 8,415,000 pixels.

Please note that the y-axis scale is different on the two histograms due to the higher bin count of dE2000's less than 1 which caused a rescale in Matlab.
« Last Edit: December 05, 2015, 02:20:28 am by Doug Gray »
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digitaldog

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As expected dE2000 numbers are much smaller for both conversions since more saturated colors tend to be harder to distinguish.
That's not why dE2000 number are lower. But that's besides the point.
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BTW, the "sample size" used is the entire image which contains 8,415,000 pixels.
So the original image was resampled. The original image is 7500000 pixels. How did you resample? 
You do know there is a V4 sRGB LUT based profile with a perceptual table and no, it's not going to solve every issue mapping a wide gamut original to sRGB. Considering that sRGB is ideal for one use, output to the web/mobil devices and that's a enormous crap shoot due to how those devices may or may not be calibrated or color managed, I'm still not sure what you're proposing that has a practical usage. 
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bjanes

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No Voodoo, sRGB gets converted to the output color space for the printer. Just as I can't send sRGB either, hence my question to you about printing sRGB. There's no such thing as an sRGB printer. However, a lab can demand an sRGB file to convert to their output color space. Which is  pretty awful when the data greatly exceeds sRGB as does the printer.

The web and thus sRGB are the lowest common denominator and it's kind of foolish to throw the baby out with the bath water when you intend to print that data too.

I agree that when one is dealing with a wide gamut printer such as the current Epson Pro line of printers, one should use ProPhotoRGB as the working space and print using a profile for the printer/paper combination. However, when looking at the profile of the Fuji Frontier LP7700 printer at my local Costco, the printer gamut exceeds that of sRGB by only minor amounts in the yellows and teal greens as shown here. The profile was downloaded from the Drycreek.com web site, which supplies profiles for various labs.



Using a wire frame rather than solid color for sRGB better demonstrates where sRGB exceeds the gamut of the Frontier.



This gamut for the printer is smaller than the one you provided for the Frontier, perhaps a different model or with different paper. Or perhaps from a less accurate profile.



One should applaud Costco for providing profiles for their printers, allowing users to submit images with the printer profile after applying the preferred rendering intent rather than merely submitting the files in sRGB for printing. However, in practice I find there is little difference in results when one uses the profiles or merely submits in sRGB. In the latter instance, the lab converts from sRGB to the printer profiled space and one has no control over the rendering intent. When using this option, one must use the Autocorrect option, which performs other optimizations in addition to selecting the rendering intent.

With this Costco lab, submitting the images in sRGB has few downsides.

Comments are welcome.

Bill
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Mark D Segal

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First, let me repeat I am totally with Andrew about not using sRGB or any smaller working gamuts than can be printed. This was an experiment to see how close one can come to representing an image in sRGB which bears the closest resemblance to a full gamut print. For instance to supply catalog images.

If anyone's interested, I can supply the matlab source code that runs this.

The image is from Andrew Rodney's printer gamut/profile test program available on his site. It consists of many highly colorful components some of which are in the full RGB space of ProPhoto. He calls it the "Printer Gamut Test File." It's particularly useful to see how out of gamut colors get printed and allows you to examine how profiles handle these colors. Some canned profiles are seriously flawed.

Attached is three images and a black and white image of the relative DeltaE in each location in the image. For these, black means DeltaE=0, White corresponds to DeltaE of 48 which occurs in locations where the ProPhoto pixel colors are extremely far from what can be rendered.

The average DeltaE was 4.3 for the modified approach (convert to printer, then sRGB) and 7.1 for the traditional approach of (convert to sRGB) before printing.

This is interesting, but for analytical purposes I think one needs two kinds of measurement: firstly, what would be the dE (1976) values for all those colours that are within the gamuts of both the printer profile and the sRGB working space; secondlym what would be the dE (1976) values for all those colours that are outside the one or the other, repeating this exercise for both RelCol and Perceptual RI. I suspect, though I don't know for sure, that the first set of measurements may show very little difference, while for the second, we may find an explanation in how OOG colours get remapped.
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Doug Gray

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But that's besides the point. So the original image was resampled. The original image is 7500000 pixels. How did you resample? 
I didn't. The file is the gamut not printer test file: "Gamut_test.file_flat.tiff", 2550x3300, 300 dpi, 16 bit, Authors "Andrew Rodney."

http://www.digitaldog.net/files/Gamut_Test_File_Flat.tif
Quote

You do know there is a V4 sRGB LUT based profile with a perceptual table and no, it's not going to solve every issue mapping a wide gamut original to sRGB. Considering that sRGB is ideal for one use, output to the web/mobil devices and that's a enormous crap shoot due to how those devices may or may not be calibrated or color managed, I'm still not sure what you're proposing that has a practical usage.

Yes, thanks for mentioning that. I recall looking at that briefly some time ago but not for this reason. I'll have to see how it behaves for this purpose.

Please note that the only reason I was proposing this was as an alternative offering a closer color match when representing what a particular large gamut print process produces in web ready sRGB.

Of course your argument about the wide range of actual color rendered by real world devices that presumably were designed to approximate sRGB to some degree is on point but there is no reason to add error on top of error.
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ErikKaffehr

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Hi Bill,

I see two cases:

1) Both photographer and lab know what they are doing. Post your image in any RGB that does not clip colours. Adjust colours to fit within the proofing profiles provided by the lab.

2) Photographer, lab or both don't know what they are doing, send sRGB.

sRGB works mostly. More importantly, if any part of the colour management workflow is broken sRGB is a good fallback option.

But, for best results, work with a lab that acknowledges embedded profiles and gives you an option to print without adjustments.

The lab I use has a service where they print the image as is. No manual controls. Half the price and fast turnaround time.

Best regards
Erik

Best regards
Erik

I agree that when one is dealing with a wide gamut printer such as the current Epson Pro line of printers, one should use ProPhotoRGB as the working space and print using a profile for the printer/paper combination. However, when looking at the profile of the Fuji Frontier LP7700 printer at my local Costco, the printer gamut exceeds that of sRGB by only minor amounts in the yellows and teal greens as shown here. The profile was downloaded from the Drycreek.com web site, which supplies profiles for various labs.



Using a wire frame rather than solid color for sRGB better demonstrates where sRGB exceeds the gamut of the Frontier.



This gamut for the printer is smaller than the one you provided for the Frontier, perhaps a different model or with different paper. Or perhaps from a less accurate profile.



One should applaud Costco for providing profiles for their printers, allowing users to submit images with the printer profile after applying the preferred rendering intent rather than merely submitting the files in sRGB for printing. However, in practice I find there is little difference in results when one uses the profiles or merely submits in sRGB. In the latter instance, the lab converts from sRGB to the printer profiled space and one has no control over the rendering intent. When using this option, one must use the Autocorrect option, which performs other optimizations in addition to selecting the rendering intent.

With this Costco lab, submitting the images in sRGB has few downsides.

Comments are welcome.

Bill
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bjanes

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sRGB works mostly. More importantly, if any part of the colour management workflow is broken sRGB is a good fallback option.

But, for best results, work with a lab that acknowledges embedded profiles and gives you an option to print without adjustments.

The lab I use has a service where they print the image as is. No manual controls. Half the price and fast turnaround time.

Best regards
Erik

My local Costco (wholesale big box store in the USA) offers the latter option to print the image as is and does provide profiles. Since the gamut of their Frontier/Paper combination is less than that of sRGB for most colors, one often faces the same problems as when trying to fit the gamut of a ProPhotoRGB image to the gamut of the printer. Perceptual rendering seldom accomplishes this when one is dealing with wide gamut images such as colorful red flowers. In these cases, the best solution is to use a wider gamut printer/paper combination.

Regards,

Bill
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digitaldog

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I agree that when one is dealing with a wide gamut printer such as the current Epson Pro line of printers, one should use ProPhotoRGB as the working space and print using a profile for the printer/paper combination.
See the post on soft proofing workflow if you haven't already: http://forum.luminous-landscape.com/index.php?topic=106264.0;topicseen
The point is, few of us know when or where we will output or master files as Jeff correctly calls them. It might be a Frontier today, an Epson P800 tomorrow. Depending on the raw processor, the gamut potential will be ProPhoto RGB. So expect in rare or special cases, most of us don't know what output device an image might land upon and ProPhoto RGB makes the most sense (to me and others) as the working space for the master image.



Quote
However, when looking at the profile of the Fuji Frontier LP7700 printer at my local Costco, the printer gamut exceeds that of sRGB by only minor amounts in the yellows and teal greens as shown here. The profile was downloaded from the Drycreek.com web site, which supplies profiles for various labs.
I can't speak specifically to that profile's gamut or the printer of course. But I've provided gamut maps from devices I have measured and they exceed sRGB gamut enough that sRGB isn't an optimal working space for those devices. Output to the web or mobile devices, fine.
Here's a plot of a LightJet on Fuji MATT paper versus Adobe RGB (1998) and as you can see, the LightJet is larger in gamut in some areas. Why clip those colors?



Here's a Frontier I again profiled (using ProfileMaker Pro like the above profile) again compared to Adobe RGB (1998), again, some clipping albeit as you suggest, not much.





Again, I can't speak to the gamut plots you've produced, only the ones based on profiles I've built and they appear to show that even Adobe RGB (1998)'s gamut isn't large enough to totally encompass those output devices. I'd be happy to send you the profiles if you wish.


Based on what I see above, based on how I process my raw data and with the product I use, based on I might output a master image I've spent hours working on, I'm sticking with encoding into ProPhoto RGB.

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Doug Gray

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This is interesting, but for analytical purposes I think one needs two kinds of measurement: firstly, what would be the dE (1976) values for all those colours that are within the gamuts of both the printer profile and the sRGB working space; secondlym what would be the dE (1976) values for all those colours that are outside the one or the other, repeating this exercise for both RelCol and Perceptual RI. I suspect, though I don't know for sure, that the first set of measurements may show very little difference, while for the second, we may find an explanation in how OOG colours get remapped.
I'm pretty sure you are right re the set of colors inside sRGB and the printer's gamut. However, the reason I started investigating whether this was possible is just the observation that the way gamut clipping is done by Photoshop et al from a matrix based color space to a smaller matrix based color space is so simple it was likely not optimal. Levels after matrix conversion are just simplistically clipped at 0 and 255. Out of gamut conversions from ProPhoto RGB to sRGB should try to use a technique that comes closer to the sRGB gamut boundary.
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digitaldog

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  • Andrew Rodney
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Please note that the only reason I was proposing this was as an alternative offering a closer color match when representing what a particular large gamut print process produces in web ready sRGB.
I understand that and see no reason why that would be at all useful. Why funnel everything to the least usable RGB working space which is only appropriate (today) for one use: internet/mobil device viewing?
The ONLY reason I'd cross render my Epson to match a smaller gamut like SWOP V2 is if I wanted to make a proof to simulate that output before going to a press that conforms to SWOP V2. Why cripple the output to print to something lesser than it is? And again, the sRGB representation you see on your display could and often does look vastly different than what someone else would see from the same numbers on a web page? It's impossible to proof and pointless too. I'm still struggling to understand what your technique does other than cripple the print output.
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