Luminous Landscape Forum

Raw & Post Processing, Printing => Colour Management => Topic started by: Coloreason on September 08, 2011, 01:16:46 pm

Title: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on September 08, 2011, 01:16:46 pm
 What's  the point or benefit of using color spaces like ProPhoto RGB which vastly exceeds the visible spectrum?
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on September 08, 2011, 01:23:44 pm
http://www.adobe.com/digitalimag/pdfs/phscs2ip_colspace.pdf
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on September 08, 2011, 01:33:06 pm
What's  the point or benefit of using color spaces like ProPhoto RGB which vastly exceeds the visible spectrum?

To hold colors, such as e.g. intensive (ly saturated) yellow hues as found in nature
by means of a simple construct with just three R/G/B primary colors.

Peter

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Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on September 08, 2011, 03:04:32 pm
Thank you for the input :)
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Waeshael on September 11, 2011, 06:16:29 pm
Technically there is no color space that can exceed the visible spectrum, because colors are made by the brain. What the camera collects is light of various wavelengths from long to short. The sensor just captures the photons from these various wavelengths and counts them up and says there were 2 million counts for the long wavelength,  3 million counts for the middle wavelength, and zero counts for the shortest wavelength, and if the human visual system experienced this mix of wavelengths it would create the sensation of something it calls yellow. The camera software attempts to emulate what the brain would produce by sending various signals to the monitor which has a matrix of red, green, and blue LEDs. It stimulates the right combination of LEDs to produce a sensation in the brain of "yellow." These signals are nothing like the original wavelengths of light coming from the scene - but they have the same effect on us as if we were at the scene - well almost. There is actually no "color" in nature.
So the purpose of color management is to create something from a monitor display, or from a film, or a print, that makes us believe we are seeing the wavelengths of light that were coming at us in the original scene. Ha-ha. So don't sweat it; the technology isn't available to do this right.

It is true that the cameras can detect wavelengths of light that we can't recreate in our brains - very long wavelengths and very short. In addition cameras can create combinations of signals that are beyond what the monitor can display because the RGB color system that is in most electronic display systems is very limited in what it can produce - no bright yellows and no deep reds for instance. Printers on the other hand can produce bright yellow, and a whole lot of other colors that the RGB system can't make.
 So, do you want the final image to display colors you can't see on your monitor -If you have see "kodachrome" -like colors in the original scene, and these colors are important to you, you can set up your color management system to save those "color" conversions and move them to the printer, even though you won't be able to see them on the display monitor. The printer paper/ink selection can then print those "kodachrome" colors.

If you are shooting for the web, then you should start with sRGB color space and continue with it to the final JPEG for the web. Older web browsers don't color manage and anything other than sRGB leads to flat pictures. If your end viewer is looking at your pictures on a laptop or an LED display, don't worry about working in a color space bigger than the monitors can display - which is sRGB. (there are monitors with a bigger color space but they have more imaging issues that you would probably want to deal with. Barco sells them for $10,000 + for medical use.)

I use a big color space to work in and I do convert my captured data (either in camera or in the RAW converter) to at least "adobe 1998" color space, because I do a lot of PP on my images and I need "elbow room" to move colors around without them getting "scrunched" by a limited color space. In the end I have to convert to sRGB to show them on the web - though for my friends they get images profiled for something larger in case the end result is to be a print.

People that make a living producing heirloom quality prints spend a great deal of time and money dealing with color management issues, and I would defer to their teaching if you decide to head in that direction - much useful teaching is right here at TLL.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: ErikKaffehr on September 14, 2011, 12:50:21 am
Hi,

The short answer is that to be able to describe as many visible colors as possible you need a color space that contains colors that are outside our color vision.

A somewhat longer answer is that RGB color is described by three primaries, name Red, Green and Blue. These primaries bound a triangle which defines the colors that the RGB can describe. To enclose all colors that can be resolved by human vision this bounding triangle needs to be larger than the area resolved by the human eye.

The "horseshoe-diagram" is bounded by spectral colors, that are fully saturated. The largest color spaces like "Prophoto RGB" have primaries outside the "horseshoe-diagram" and I don't think that those colors are physically possible as they would be more saturated than spectral colors. They are mathematical constructs needed to be able to represent all colors using the primaries.

Best regards
Erik

What's  the point or benefit of using color spaces like ProPhoto RGB which vastly exceeds the visible spectrum?
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on September 14, 2011, 11:29:26 am
Large gamut color spaces, or working spaces as they should be referred to, allow mapping of colors more easily when editing. All color viewing devices like display's and printers have unique 3D color gamut models that allow this mapping to occur using apps like Photoshop.

One's display may be capable of displaying one particular hue of cyan over another and a larger working space will make it easier to get there.

This was the argument against color management (especially with regards to calibrating and profiling displays) from the beginning by those who insisted on using their monitor as their working space because they saw they could get/retain colors achieved in legacy files edited in that space.

They didn't understand that their computer was a dumb machine and must be told everything even when a new standard of encoding data for ICC based color management was introduced that seemed to prevent them from doing things the old way when what was really happening was getting everyone on the same page (map) requiring everyone have the same directions for getting there.

Large working spaces allow mapping through edits of all possible colors produced by the device (display) more easily. You can see this just by assigning a large working space to a new Photoshop document and examining colors in the Color Picker compared to assigning like say sRGB to a new PS doc. They will be noticeably different especially when viewed on a wide gamut display.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on September 14, 2011, 11:36:50 am
Large gamut color spaces, or working spaces as they should be referred to...
Only if they are working spaces. There are wide gamut color spaces that are not wide gamut working spaces. This is not simply semantics! When I convert my images into an output color space and edit it, its not in a working space and can be wide gamut.

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One's display may be capable of displaying one particular hue of cyan over another and a larger working space will make it easier to get there.

Yes. And the color that is out of display gamut may be reproducible on another device so its important not to throw the baby out with the bath water just because one device in the change is of a lower, limited gamut.

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This was the argument against color management (especially with regards to calibrating and profiling displays) from the beginning by those who insisted on using their monitor as their working space because they saw they could get/retain colors achieved in legacy files edited in that space.

Prior to Photoshop 5, its the only way we could work. Until that product, the masses had to edit using their display color space as a working space (the term working space was not yet generally even understood by users)

Quote
They didn't understand that their computer was a dumb machine and must be told everything even when a new standard of encoding data for ICC based color management was introduced that seemed to prevent them from doing things the old way when what was really happening was getting everyone on the same page (map) requiring everyone have the same directions for getting there.

We had ICC color management long before Photoshop 5. We just had to use our display color space as our working space. We had a working space called ColorMatch RGB years before Photoshop 5 and the concept of a working space (or differing working spaces).
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on September 14, 2011, 01:20:31 pm
The short answer is that to be able to describe as many visible colors as possible you need a color space that contains colors that are outside our color vision.

A somewhat longer answer is that RGB color is described by three primaries, name Red, Green and Blue. These primaries bound a triangle which defines the colors that the RGB can describe. To enclose all colors that can be resolved by human vision this bounding triangle needs to be larger than the area resolved by the human eye.

The key moment probably was when the red lamp had to be moved to the other side of the target color to be matched by three R/G/B light sources, thus delivering a negative r matching function, in the original color matching experiment.
I think it was before 1976 - though I was not there  ;)

Peter

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Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on September 14, 2011, 03:06:00 pm
Thanks for the clarifications, Andrew.

That ColorMatchRGB PressView monitor must've been one gorgeous display back then. Wonder how it rendered and matched CMYK cyan viewed under a D50 light source? Under the Solux 4700K desk lamp it's insanely intense and lovely to look at, but I swear that color plays tricks on my eyes.

My fairly new Dell 2209WA sRGB-ish LCD can't even come close to rendering that cyan properly, but my old G5 iMac that finally died could.

But I'm not understanding your mentioning the differences of working spaces and color spaces with regard to wide gamut. If we don't use these mathematically synthetic spaces as working and archiving color spaces then what other use are they for?

Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on September 14, 2011, 04:13:26 pm
But I'm not understanding your mentioning the differences of working spaces and color spaces with regard to wide gamut. If we don't use these mathematically synthetic spaces as working and archiving color spaces then what other use are they for?

A working space is a synthetically created theoretical color space built with simple values, white point, chromaticity values for RGB and a TRC Gamma. They are based on a Quasi-Device Independent, non real world emissive like device. They are well behaved meaning that R=G=B is always neutral. They can be low or high (wide) gamut. We can have a wide gamut color space (convert ProPhoto to Epson 9800 Luster) that is not a working space. Its still a color space. Its still wide gamut (assuming everyone agrees what is wide). Its not a working space. So:

Large gamut color spaces, or working spaces as they should be referred to...

In some cases, they should not necessarily be referred to as working spaces.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on September 14, 2011, 10:55:34 pm
Oh, not the in-depth and enlightening explanation I was expecting, Andrew.

Next time I'll pick my words more carefully and be more precise. I think I did make a valid point about working spaces which is the what the topic was about since it reads...

What's the point of using color spaces exceeding the visible spectrum? I assumed the OP was referring to ProPhotoRGB and other wider synthetic color spaces. Never implied or thought a printer color space (Epson 9800 Luster) exceeded the visible spectrum.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on September 15, 2011, 10:05:57 am
What's the point of using color spaces exceeding the visible spectrum?

They allow us to encode colors that fall outside other such color spaces where the limits of the primaries fall within visible spectrum.

If you want to fit a round peg in a square hole, there has to be overlap. Even if that overlap wastes some space (the shape has to be round).
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on September 22, 2011, 02:51:53 pm
Thanks for the answers everyone, and sorry for the later reply
These explanations make perfect sense:
Quote
primaries bound a triangle which defines the colors that the RGB can describe. To enclose all colors that can be resolved by human vision this bounding triangle needs to be larger than the area resolved by the human eye.
Quote
If you want to fit a round peg in a square hole, there has to be overlap. Even if that overlap wastes some space (the shape has to be round).

by the way, talking about working spaces, some explanations here made me think that there may be two different meaning of this. AFAIK working spaces is a feature (tool) in color managed programs like Photoshop, Illustrator, etc. to assign color profiles to new documents or placed/ copied documents depending on user's policy and also to display untagged documents in a certain (space) profile. Also the choice of working spaces in the color settings affect the color values in the color palettes with converting the values when switching between palettes with different color models like RGB and CMYK, - the values represent the color in the space (profile) selected for a working space. In other words, I thought all a working space (profile) is simply an option in the color settings of these programs to choose for a special propose one of the color spaces(profiles) available.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: RazorTM on September 25, 2011, 08:47:37 pm
http://www.adobe.com/digitalimag/pdfs/phscs2ip_colspace.pdf

That's an excellent explanation of the basics.  Thanks for the link!!!
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on September 26, 2011, 03:01:15 am
Quote
AFAIK working spaces is a feature (tool) in color managed programs like Photoshop, Illustrator, etc. to assign color profiles to new documents or placed/ copied documents depending on user's policy and also to display untagged documents in a certain (space) profile. Also the choice of working spaces in the color settings affect the color values in the color palettes with converting the values when switching between palettes with different color models like RGB and CMYK, - the values represent the color in the space (profile) selected for a working space. In other words, I thought all a working space (profile) is simply an option in the color settings of these programs to choose for a special propose one of the color spaces(profiles) available.

Some of what you said is right and some of it's wrong but it's way too complicated to sort out and explain.

I can assure you what I said about Working Spaces is correct with regard to Editing Spaces and how it works with the color gamut of your monitor. The bigger the Working/Editing/Color Space the easier it is to utilize the monitor's full color gamut editing color in images more so for Raw over jpegs from a digital camera which "Encode/Write" their jpeg RGB data to a Working Space, Editing Space, Color Gamut, Color Space or Profile (usually sRGB or AdobeRGB). The terms are all interchangeable in representing that hole to fit the peg into.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 03, 2011, 10:57:32 pm
Some of what you said is right and some of it's wrong but it's way too complicated to sort out and explain.

I can assure you what I said about Working Spaces is correct with regard to Editing Spaces and how it works with the color gamut of your monitor. The bigger the Working/Editing/Color Space the easier it is to utilize the monitor's full color gamut editing color in images more so for Raw over jpegs from a digital camera which "Encode/Write" their jpeg RGB data to a Working Space, Editing Space, Color Gamut, Color Space or Profile (usually sRGB or AdobeRGB). The terms are all interchangeable in representing that hole to fit the peg into.

Hi, thanks for your reply. May be my understanding about working spaces is incomplete but I'm pretty sure what I said is perfectly correct. I think what you and some others mean when they say "Working spaces" is another term for "Color spaces" described in color profile files. And often people use "Color profile" and "Color space" meaning the same thing which make sense. I guess some people also use "Working space" meaning the same thing too because any color profile can be assigned and used as a working space. However, I think this adds to the confusion and believe that it will be more clear if using the term "Working space" only means the currently assigned/used working space in a color managed program.
Just my 2 cents :)
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on October 04, 2011, 01:01:35 pm
You don't assign any profile, color space, working space to an image that doesn't already have one embedded. You have to KNOW what color space/profile that image's RGB data was ENCODED/WRITTEN to for images that don't have an embedded profile/color space/working space (like some jpegs from certain brands/models of digital cameras). The intended preview will be messed up/not as intended if assigning the wrong color space to an image.

Your use of the term assign is what's confusing the issue because it makes people think it's OK to assign (as it's worded in Photoshop) any color space to an image. Maybe you're using the term loosely and even then I wouldn't know how it would apply in this case but regardless, I'ld caution against using this term for the reasons lined out above.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 05, 2011, 02:09:11 pm
You don't assign any profile, color space, working space to an image that doesn't already have one embedded. You have to KNOW what color space/profile that image's RGB data was ENCODED/WRITTEN to for images that don't have an embedded profile/color space/working space (like some jpegs from certain brands/models of digital cameras). The intended preview will be messed up/not as intended if assigning the wrong color space to an image.

Your use of the term assign is what's confusing the issue because it makes people think it's OK to assign (as it's worded in Photoshop) any color space to an image. Maybe you're using the term loosely and even then I wouldn't know how it would apply in this case but regardless, I'ld caution against using this term for the reasons lined out above.

When I say "assign" I mean in color managed programs like Photoshop, you open the Color Settings window and in the Working Spaces section, choose (assign) a color profile for RGB, CMYK, and etc. My point was that because any color profile can be selected (assigned) for a working space, some people like you and even the author of this Adobe tutorial  (http://www.adobe.com/digitalimag/pdfs/phscs2ip_colspace.pdf) use the term "Working Space" instead of  the "Color Space" of a color profile. I believe this is confusing because this setting does nothing to a document with a color profile (as you said, you don't assign to an image with a profile) but only affects (assigns) the working space profile for display (altering the video card color values only) of untagged images (images without color profiles). The selected working space in the Color Settings also appears for the default color space (to be assigned) when you choose File > New to create a new document but you can select any other color profile from the menu.

Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: MarkM on October 05, 2011, 03:39:21 pm
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some people like you and even the author of this Adobe tutorial use the term "Working Space" instead of  the "Color Space" of a color profile.

People use the term to refer to color spaces that are designed to be used as working space such as AdobeRGB(1998). Just because you can assign your printer profile as the working space in photoshop's color settings doesn't make it a working space any more than eating soup with a fork makes a fork a spoon.

I think Andrew answered the question perfectly well up above in response #10.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 05, 2011, 03:44:31 pm
My point was that because any color profile can be selected (assigned) for a working space, some people like you and even the author of this Adobe tutorial  (http://www.adobe.com/digitalimag/pdfs/phscs2ip_colspace.pdf) use the term "Working Space" instead of  the "Color Space" of a color profile.

A working space is a color space. But its a particular kind, one used for image editing and archiving, based on a well behaved theoretical (emissive) device. Its Quasi-Device Independent. An output space is just that (a color space that describes some printer). In input space is also a color space of a capture device like a scanner or camera. So a working space is a color space. But not all color spaces are working spaces.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 05, 2011, 04:56:20 pm
People use the term to refer to color spaces that are designed to be used as working space such as AdobeRGB(1998). Just because you can assign your printer profile as the working space in photoshop's color settings doesn't make it a working space any more than eating soup with a fork makes a fork a spoon.

I think Andrew answered the question perfectly well up above in response #10.


I perfectly understand the reasons but I disagree with you and believe that the use of the term "Working spaces" is confusing when used for that purpose. A "Common standard" color space is a much more appropriate term. For example, you could have sRGB selected as your working space in the Color Settings, your document color profile could be AdobeRGB, and you could be also editing this document often soft proofing it with CMYK US Web Coated Swap v2. By your definition all of these profiles are working spaces and this makes it confusing answering the question about what working space you are currently using.
I also disagree that assigning a color profile like your printer's profile as a working space doesn't make it as such. It does technically and practically. If you more often need to examine than edit untagged photos how they will look printed, it is more practical to assign your printer profile as your working space than soft proofing it because that way it is less work. Another example, I use my monitor profile as a working space in Photoshop because most of the time I create images with 3D programs and want to bring them to color management. All major 3D programs are not color managed so I have to make color choices referring to my monitor's color space and save untagged files. When I open them in Photoshop and convert them to a "common standard" color space that you call "working space" like sRGB they convert appropriately from the color space of my monitor so, my monitor color profile in this case becomes a perfectly legitimate working space.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 05, 2011, 05:24:54 pm
I also disagree that assigning a color profile like your printer's profile as a working space doesn't make it as such. It does technically and practically. If you more often need to examine than edit untagged photos how they will look printed, it is more practical to assign your printer profile as your working space than soft proofing it because that way it is less work.

Working spaces are well behaved (R=G=B). That's only the case with these theoretically constructed spaces. And you would not assign a profile to any document unless it has no ICC profile associated with it or (far less likely) its the wrong profile association. All properly conducted color space conversions (to such a space) would assign the profile as the conversion takes place.

IF everyone on the planet had properly tagged images, Adobe could remove the Assign Profile command from Photoshop. It would be unnecessary.

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Another example, I use my monitor profile as a working space in Photoshop because most of the time I create images with 3D programs and want to bring them to color management.

Because your 3D software isn't smart enough to be color managed. It produces an untagged document which is previewing the numbers by simply sending them to your display. It has no idea your display is calibrated, it has no idea what a color space is. You are treating this data like Photoshop 4 and earlier when there was no color management.

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When I open them in Photoshop and convert them to a "common standard" color space that you call "working space" like sRGB they convert appropriately from the color space of my monitor so, my monitor color profile in this case becomes a perfectly legitimate working space.

Actually it doesn't. Its simply a source profile to define the color numbers. Not until you convert from display to RGB working space do you gain the benefits of an RGB working space unless you're darn lucky and the display behaves in all color space where R=G=B is neutral. You should be assigning the display profile to the data (because its untagged thanks to the 3D app), then converting to sRGB. Assign and Convert are quite different beasts.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Schewe on October 05, 2011, 05:58:30 pm
I perfectly understand the reasons but I disagree with you and believe that the use of the term "Working spaces" is confusing when used for that purpose.

Open Photoshop...go to the Color Settings dialog and look at the term Adobe used: Working Spaces. So, when you are talking about editing in Photoshop, would it not be wise to use the same term that Adobe used? A Working Space can be RGB, CMYK, Gray Gamma or Dot Gain...calling them anything other than a Working Space would be confusing...
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 05, 2011, 05:59:31 pm
Working spaces are well behaved (R=G=B). That's only the case  ...
I understand perfectly what these color spaces are, the question is about calling them "Working spaces" when the section in the Color Settings of the Adobe products is also called "Working Spaces" and allowing you to choose any other profile. I don't mind one of the two remains being called "Working Spaces" but not both because this is confusing, isn't it? And that was the whole point of my input here. If only the profiles circled in red are considered as "Working Spaces" then that section should not be named "Working Spaces" or on the other hand if we agree "Working Spaces" is a good name for that section then the profiles circled with red should be called something else.

(http://img856.imageshack.us/img856/5153/workingspaces.jpg)

... Actually it doesn't. Its simply a source profile to define the color numbers. Not until you convert from display to RGB working space do you gain the benefits of an RGB working space unless you're darn lucky and the display behaves in all color space where R=G=B is neutral. You should be assigning the display profile to the data (because its untagged thanks to the 3D app), then converting to sRGB. Assign and Convert are quite different beasts.
I'm not sure if you understood me here. Having an image that was created referring to monitor's color space opened in Photoshop when the monitor profile is selected as a working space in the Color settings and then Edit > Convert to sRGB is the same if you first Edit > Assign the monitor profile to the image and then Edit > Convert to sRGB. Both ways do exactly the same thing but the second way is more work if you do that all the time.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 05, 2011, 06:11:46 pm
Open Photoshop...go to the Color Settings dialog and look at the term Adobe used: Working Spaces. So, when you are talking about editing in Photoshop, would it not be wise to use the same term that Adobe used? A Working Space can be RGB, CMYK, Gray Gamma or Dot Gain...calling them anything other than a Working Space would be confusing...
From that section as I showed with the image in the previous post you can select your printer, monitor, and all available profiles for a working space and because of that they also should be called "Working spaces" which makes perfect sense. The problem is that some people consider and call only certain color spaces (in red on the image) as working and this is confusing. I perfectly understand that these color spaces are different than the rest and should be called with a special name but that name should not be the same as the name of the section containing all other profiles.
As I said how would you answer the question: What is your current working space if you have this:
For example, you could have sRGB selected as your working space in the Color Settings, your document color profile could be AdobeRGB, and you could be also editing this document often soft proofing it with CMYK US Web Coated Swap v2. ...
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Schewe on October 05, 2011, 07:02:16 pm
As I said how would you answer the question: What is your current working space if you have this:

"For example, you could have sRGB selected as your working space in the Color Settings, your document color profile could be AdobeRGB, and you could be also editing this document often soft proofing it with CMYK US Web Coated Swap v2. ..."

sRGB...
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 05, 2011, 07:03:26 pm
I understand perfectly what these color spaces are, the question is about calling them "Working spaces" when the section in the Color Settings of the Adobe products is also called "Working Spaces" and allowing you to choose any other profile. I don't mind one of the two remains being called "Working Spaces" but not both because this is confusing, isn't it?

Working space is a term to describe the color space of the image you are editing: working space = editing space. RGB working spaces, specifically filtered by Adobe, installed by Adobe and what one should be editing in are a different story. They are simple, matrix profiles based on theoretical RGB emissive devices and are well behaved. You can edit in a non well behaved color space but why would you? The entire CMS architecture in Photoshop from 5.0 on is to divorce the display as your editing space and instead use a small group of these manufactured well behaved spaces for edit and archive.

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I'm not sure if you understood me here. Having an image that was created referring to monitor's color space opened in Photoshop when the monitor profile is selected as a working space in the Color settings and then Edit > Convert to sRGB is the same if you first Edit > Assign the monitor profile to the image and then Edit > Convert to sRGB. Both ways do exactly the same thing but the second way is more work if you do that all the time.

The 3D app has no way to tag the data. You have to Assign the display profile. That's the role of the Assign Profile command. Unless you setup Photoshop where the RGB Working Space is set for that display profile (and that's a bad idea), Photoshop has no way to know what the RGB values of that data relate to. The RGB Working Space selection play a role as the assumption of all untagged data even if that isn't the case. In the settings you show, Photoshop would assume all untagged data is sRGB but that's not the case in the 3D image. It has to be assigned the display profile first, then it has to be converted to an RGB Working Space like sRGB (or you lose an incredible feature of well behaved RGB working spaces).
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on October 05, 2011, 07:13:41 pm
... then the profiles circled with red should be called something else.

How about:  Common Standard Working Spaces.

Hope this helps,
although semantics are not my strengths.

Peter

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Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: fdisilvestro on October 05, 2011, 08:47:01 pm
I like the term used in the book Real World Photoshop CS3 by Blatner, Chavez & the late Fraser: "Built-in Working Spaces".

There is an important distinction in the color settings dialog in Photoshop: If you select "Fewer Options" then only the Built-in Working Spaces will appear in the drop downs for RGB, CMYK, Gray & Spot. When you select "More Options", Photoshop lets you select also Output spaces as your working spaces. So if seeing all those output spaces in the drop downs annoy you, just select "Fewer options".

Now, why is it recommended to use built-in working spaces? Well, first, as it has been previously mentioned by Andrew Rodney, they are Gray balanced, meaning R=G=B will always produce a neutral gray.

The other important property is that they are aproximately perceptually uniform. Quoting Real World Photoshop CS3 by Blatner, Chavez & Fraser:

Quote
Perceptually uniform...Meaning that changing each channelīs numeric values in the image by the same increment results in about the same degree of visual change, no matter whether itīs in the highlights, the midtones, the shadows, the pastels, or the saturated colors. Again, device spaces generally donīt work that way.

Instead of using an output space as working space it would  be better to use a built-in working space and use Soft-proofing.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 05, 2011, 09:51:23 pm
How about:  Common Standard Working Spaces...
I like the term used in the book Real World Photoshop CS3 by Blatner, Chavez & the late Fraser: "Built-in Working Spaces". ...
;D Both will work and anything else too that is not exactly "Working space". Though if I have a say, I prefer the shortest possible like just "Common" or "Built-in".
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 05, 2011, 09:52:55 pm
Working space is a term to describe the color space of the image you are editing: working space = editing space. ...
But  here's the confusion from this, Schewe in his post #26 replied to my question "sRGB" and that answer defies your definition that working space = editing space because in that case the selected sRGB profile in the color settings doesn't have any effect on the editing of the image which is with Adobe RGB profile.
... You can edit in a non well behaved color space but why would you? The entire CMS architecture in Photoshop from 5.0 on is to divorce the display as your editing space and instead use a small group of these manufactured well behaved spaces for edit and archive. ...
I agree with you, especially if you rely on the numbers of the color values to make sense, and I don't edit in device specific color spaces - in the example I gave the monitor color profile selected for the working space affects only the conversion to "common standard/bult-in working space ;D" for example sRGB and has no further effect on the editing - as you know the color profile selected for a working space in the Color settings does not affect images with profiles. But back to your question, hypothetically speaking,  I can think of a situation where editing in monitor color space can make sense. If you are creating art from scratch say, a painting using tools like brushes, and picking colors using the color palettes without caring what the numbers for those colors are, and if you have a well calibrated monitor and a profile that describes correctly the meaning of the colors as perceived by the eye, the artwork when saved with the monitor profile, at any time later can be perfectly converted to a wider "common standard" space. I think this can be especially useful with the newer wider gamut monitors where the artist  doesn't want to limit his color palette to a narrower common color space and at the same time doesn't want to use wider color space like Prophoto RGB and deal with colors that monitor cannot show. I think this could be a valid strategy for creating and archiving artwork for the future when all monitor will be with much wider gamut.
The 3D app has no way to tag the data. You have to Assign the display profile. That's the role of the Assign Profile command. Unless you setup Photoshop where the RGB Working Space is set for that display profile (and that's a bad idea), Photoshop has no way to know what the RGB values of that data relate to. The RGB Working Space selection play a role as the assumption of all untagged data even if that isn't the case. In the settings you show, Photoshop would assume all untagged data is sRGB but that's not the case in the 3D image. It has to be assigned the display profile first, then it has to be converted to an RGB Working Space like sRGB (or you lose an incredible feature of well behaved RGB working spaces).
May be I wasn't clear but as I said more than once, I assign my monitor profile for the working space in the Color settings. This assigns the monitor profile to the untagged image for display purpose with the video card but doesn't affect the file and the image remains to be reported as untagged. The image is displayed properly as intended because it was created referring to the same monitor and the monitor profile describes correctly how monitor displays colors. Displaying of the image is the same as if choosing Edit > Assign and choosing the monitor profile - the video card does exactly the same but in addition to that the profile (the meaning of the colors) is embedded in the file when saved.  So, in both cases when after that you choose Edit > Convert to sRGB the result is identical. And if one have to do this operation most of the time I don't see as to why assigning the monitor profile as a working space in the color settings is a bad idea - to say it again in other words, it is just a tool for conversion and has no effect on the editing.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 06, 2011, 10:11:00 am
But  here's the confusion from this, Schewe in his post #26 replied to my question "sRGB" and that answer defies your definition that working space = editing space because in that case the selected sRGB profile in the color settings doesn't have any effect on the editing of the image which is with Adobe RGB profile.

Both sRGB and Adobe RGB are working spaces! You donít have to be currently editing in one for that to be a fact.

Quote
But back to your question, hypothetically speaking,  I can think of a situation where editing in monitor color space can make sense. If you are creating art from scratch say, a painting using tools like brushes, and picking colors using the color palettes without caring what the numbers for those colors are, and if you have a well calibrated monitor and a profile that describes correctly the meaning of the colors as perceived by the eye, the artwork when saved with the monitor profile, at any time later can be perfectly converted to a wider "common standard" space.


No, it doesnít make sense. Its not well behavied. Its highly device dependant and has lots of idiosyncrasies of this single output device. There is zero reason to start a blank document in such a space. Create one in sRGB. Or Adobe RGB (1998) if you want a wider gamut (you can always convert an iteration back to sRGB for posting to the web). The only time the display profile should ever, ever be accessed in Photoshop is in the case you outline. You have untagged data, created by a stupid non color management app that you want to maintain the color appearance in a color managed app. You assign the display profile in Photoshop to maintain the color appearance then you should convert to a well behaved RGB working space like sRGB.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 06, 2011, 12:43:55 pm
Both sRGB and Adobe RGB are working spaces! You donít have to be currently editing in one for that to be a fact....
I understand that this is a fact, but what I'm saying that it is an unfortunate and confusing fact and I'm starting to wonder as to why people don't see it as such. If someone says "I use this profile for my working space" it is so general that it means almost nothing. It could be the space of the color profile selected in the Color Settings, or the embedded or soft proofing color profile of the image. It could be also someone talking about profiles like monitor or printer profiles assigned as a working space in the color settings (I gave a couple of examples when this is practical and saves time) and such person has full right to say it that way - what else he can say - "I'm using non-working color space for a working color space"? It sounds funny isn't it?

...
No, it doesnít make sense. Its not well behavied. Its highly device dependant and has lots of idiosyncrasies of this single output device. There is zero reason to start a blank document in such a space. ...
I know and agree that it is not well behaved, highly device dependent and has lots of idiosyncrasies, however I'm not sure about the zero reasons. The color spaces of most wide gamut monitors are quite different than Adobe RGB. In some areas they may extend beyond while on others undercover it. In the example I gave with an artist creating artwork from scratch simply by picking colors and painting, editing in the monitor color space will not clip it to the colors contained in both the monitor's and Adobe RGB color spaces and at the same time will insure that colors that cannot be displayed on the monitor will not be used. In such case I'm curious what could be the problem? I know that what appears to be a perfect gray may not show as perfectly equal RGB numbers and some other idiosyncrasies form that nature with certain tools, but as I said if the artist creates the artwork without any use of numbers and such tools, he can create a perfect artwork  simply by picking colors visually and painting. If the  monitor calibration and profile are done properly, artwork created in such way should be perfectly converted with preserving the color appearance to other wider color spaces.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 06, 2011, 12:55:52 pm
If someone says "I use this profile for my working space" it is so general that it means almost nothing.

How so? You now know the numbers and their associated scale. That be true if it were a working space or not. Numbers without a scale are menainless. So the sentence you propose provides some information. Why the conversation comes up is questionable but the statement is complete.

Quote
It could be the space of the color profile selected in the Color Settings, or the embedded or soft proofing color profile of the image.


Yes it could. So what? If I tell you my working space preferences in Photoshop are set such that ProPhoto RGB is loaded as my preferred working space, that tells you one thing. It can be set as such and I can open a document in sRGB and tell you this. Again, each piece of information is complete. It doesnít need to referece the other. You know what I prefer to use for my editing space (for new documents), what I expect Photoshop to assume for untagged documents (which I never encounter because they are bad news). In another sentence, Iíve told you the working space of the data Iím currently working on (sRGB) which is completely separate from the working space preferences I have set.

Quote
It could be also someone talking about profiles like monitor or printer profiles assigned as a working space in the color settings (I gave a couple of examples when this is practical and saves time) and such person has full right to say it that way - what else he can say - "I'm using non-working color space for a working color space"? It sounds funny isn't it?

Not at all. You seem to expect the term working space to carry over as an ambiguous tag and thatís not useful. If you tell me you have assigned your display profile to the 3D data because its untagged, I fully understand the numbers and their associated scale (color space). Photoshop does too and handles the data and color appearance correctly. If you tell me you opened a document from ACR in ProPhoto, that working space has nothing to do with the 3D image.

Quote
I know and agree that it is not well behaved, highly device dependent and has lots of idiosyncrasies, however I'm not sure about the zero reasons.


Give me more. Other than telling the color managed application the meaning of the numbers, why would you continue to use such a space? Its not well behavied. Its unqiue to your display based on the day you made that profile (which may be different in a few weeks). Its useless outside ICC aware applications. So inside an ICC aware app, whatís the resaon youíd stick with this color space?

Quote
The color spaces of most wide gamut monitors are quite different than Adobe RGB.

Yes they are just as the color space of sRGB gamut monitors can be quite different than sRGB. All I have to do is calibrate the display with targets that donít match sRGB and guess what? Its not sRGB. Its questionable any modern LCD that isnít using P22 phosphors produce sRGB as its defined. And they donít have to! Thatís WHY we divorce the working space from the display. If your data is in sRGB, its the same on any oneís machine. Your display profile describes one color space of one display on one day that may be different the next. Not so with sRGB or any of the synethic working spaces. Thatís why we use them!
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Schewe on October 06, 2011, 01:31:04 pm
But  here's the confusion from this, Schewe in his post #26 replied to my question "sRGB" and that answer defies your definition that working space = editing space because in that case the selected sRGB profile in the color settings doesn't have any effect on the editing of the image which is with Adobe RGB profile.

It's simple...sRGB is the Working Space (notice the caps) as determined by Photoshop. Adobe RGB is the editing space of a specific document as long as Use Embedded Profile is set as the CM policy even if the Working Space in Photoshop is different.

You're making this much more difficult than it is...the Working Space is the color space as set for one of the color modes in Photoshop. The editing space can be the Working Space or a different color space if using the embedded color space in a document.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on October 06, 2011, 02:29:27 pm
Both will work and anything else too that is not exactly "Working space". Though if I have a say, I prefer the shortest possible like just "Common" or "Built-in".

But then it is easy to built-in virtually any working space, so that it appears among the "common standard working spaces" cycled with red, by just dropping the icc profile in the corresponding Adobe > subfolder  :o

... but what I'm saying that it is an unfortunate and confusing fact and I'm starting to wonder as to why people don't see it as such. If someone says "I use this profile for my working space" it is so general that it means almost nothing. It could be the space of the color profile selected in the Color Settings, or the embedded or soft proofing color profile of the image. It could be also someone talking about profiles like monitor or printer profiles assigned as a working space in the color settings Ö

Trying to understand what is so confusing for youÖ
Are you possibly not aware that Photoshop Ė as a color managed environment Ė does a permanent RelCol conversion on-the-fly from the selected or assigned Working space to the monitor profile. For most general purposes, this equalizes the choice of Working space. Not talking about oog scenarios, etc. here.

Peter

--
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 06, 2011, 05:01:50 pm
If someone says "I use this profile for my working space" it is so general that it means almost nothing.
How so? You now know the numbers and their associated scale. That be true if it were a working space or not. Numbers without a scale are menainless. So the sentence you propose provides some information. Why the conversation comes up is questionable but the statement is complete.
I was talking about the meaning (information) of the word "working" in that statement not the information the rest of the statement gives. Because the section in the color preferences is called "working" spaces, it makes perfect sense to use the term "working" for any profile that can be selected there but by your definition it shouldn't and this makes the complication and requires additional explanation. If instead of "working", the term was something else like "common" or "built-in" or whatever to mean certain group of profiles, it would be very clear what this means and no further explanation would be required.
It could be the space of the color profile selected in the Color Settings, or the embedded or soft proofing color profile of the image.
Yes it could. So what?

Well, here's what happened - a long thread about what exactly the term "working" means and what should be the proper use of it. Hopefully I'm the only idiot in the world who can't get it, but just looking through this thread I see several posts from other people requiring additional explanation to communicate properly mostly because of this confusion with the term "working".
....Not at all. You seem to expect the term working space to carry over as an ambiguous tag and thatís not useful. If you tell me you have assigned your display profile to the 3D data because its untagged, I fully understand the numbers and their associated scale (color space). Photoshop does too and handles the data and color appearance correctly. If you tell me you opened a document from ACR in ProPhoto, that working space has nothing to do with the 3D image.
If I say, I use the color profile of my printer as a working space this should mean only that I have selected it as a working space in the color preferences and nothing else - this makes things clear. What makes thins complicated is when you and the others insist that I cannot call it a working space or that doesn't make it a working space and what not because working spaces means only a certain group of profiles. Remember, I'm not talking about what is right or wrong but simply communicating a certain setup.
...Give me more. Other than telling the color managed application the meaning of the numbers, why would you continue to use such a space? Its not well behavied. Its unqiue to your display based on the day you made that profile (which may be different in a few weeks). Its useless outside ICC aware applications. So inside an ICC aware app, whatís the resaon youíd stick with this color space?

Yes they are just as the color space of sRGB gamut monitors can be quite different than sRGB. All I have to do is calibrate the display with targets that donít match sRGB and guess what? Its not sRGB. Its questionable any modern LCD that isnít using P22 phosphors produce sRGB as its defined. And they donít have to! Thatís WHY we divorce the working space from the display. If your data is in sRGB, its the same on any oneís machine. Your display profile describes one color space of one display on one day that may be different the next. Not so with sRGB or any of the synethic working spaces. Thatís why we use them!
About this, let me put it in a form of a question. I create a new document, I assign my monitor profile to the image, I pick colors from the color palette and paint an artwork with the paint brush, I'm happy how it looks, when I finish I convert from my monitor profile to Prophoto RGB or choose to save the image with the monitor profile embedded and convert to Prophoto RGB at a later time. The questions is, will the colors change when I convert to Prophoto RGB? If not what's the problem with this workflow?
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 06, 2011, 05:05:19 pm
It's simple...sRGB is the Working Space (notice the caps) as determined by Photoshop. Adobe RGB is the editing space of a specific document as long as Use Embedded Profile is set as the CM policy even if the Working Space in Photoshop is different.

You're making this much more difficult than it is...the Working Space is the color space as set for one of the color modes in Photoshop. The editing space can be the Working Space or a different color space if using the embedded color space in a document.

Well, not sure why you say I'm making it more difficult when you basically all the time say what I'm trying to say, the words in bold from your quote are exactly what I'm trying to repeat many times in other words about what a proper definition should be. And I agree that your answer "sRGB" to my question in post #26 is the only correct answer.
... In other words, I thought all a working space (profile) is simply an option in the color settings of these programs to choose for a special propose one of the color spaces(profiles) available.

But according to Digitaldog and others, that's not it, they say working space = editing space and only a special group of profiles should be actually called "working" spaces.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 06, 2011, 05:17:14 pm
But then it is easy to built-in virtually any working space, so that it appears among the "common standard working spaces" cycled with red, by just dropping the icc profile in the corresponding Adobe > subfolder  :o
...
Where a "built-in" or if you like "common" color profiles appear on the sections of the menu is not a problem as long as we refer to them with a term not used for other things like the "Working spaces" section in the color preferences.


Trying to understand what is so confusing for youÖ
Are you possibly not aware that Photoshop Ė as a color managed environment Ė does a permanent RelCol conversion on-the-fly from the selected or assigned Working space to the monitor profile. ...
Here's the confusion, because I don't know what you mean when you say " selected or assigned Working space" I cannot tell if your statement is correct.
If by saying " selected or assigned Working space" you mean the color profile selected for a working space in the color preferences, then your statement is incorrect.
I would say it this way: Photoshop  does a permanent RelCol conversion on-the-fly from the displayed color space of the image to the monitor profile. I think this makes it more clear. Displayed color space of the image could be the soft proofing color space, if soft proofing is off then the color space of the embedded profile will be used for displaying, and if there is no embedded profile the image will be displayed in the color space of the color profile selected for the working space in the Color preferences.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: jc1 on October 06, 2011, 08:31:54 pm
Hi,

I would say it this way: Photoshop  does a permanent RelCol conversion on-the-fly from the displayed color space of the image to the monitor profile. I think this makes it more clear. Displayed color space of the image could be the soft proofing color space, if soft proofing is off then the color space of the embedded profile will be used for displaying, and if there is no embedded profile the image will be displayed in the color space of the color profile selected for the working space in the Color preferences.

Is displayed color space different from working space? Can it be any color space, either absolute (synthetic in digitaldog's article) color space or output device (printer or device dependent) color space?  Must it be sRGB or monitor (custom) color space?

As for those profiles circled with RED, my understanding is that they are preferred and recommended RGB working spaces. They are grouped for easy and direct accessibility, as icc profile has an internal name which could be different from its actual file name. Those profile names that are appearing in the selection pull-down menu are internal profile names.

jc
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 06, 2011, 10:03:35 pm
Hi,
Is displayed color space different from working space? ...
With displayed color space I mean the color space the image is being currently displayed in - that's it. In Photoshop there are 3 possible places that control this. In order of priority this is the color profile chosen in the proof setup when the proof colors is on, then the embedded profile of the image, and for images without a profile - the color profile selected for a working space in the Color Settings. So it is not necessarily a working space as defined by Digitaldog because the user can assign any color profile in those 3 places for whatever reasons they want.
...
As for those profiles circled with RED, my understanding is that they are preferred and recommended RGB working spaces. ...
:) Preferred or Recommended, that's another two beautiful names that fit perfectly for the meaning of working spaces as defined by Digitaldog.

edit:
or if the meaning of "working spaces" as defined by Digitaldog is already established in the user's community, then Adobe should change the name "Working spaces" in the Color settings to something else. I can't think of a nice name but how about "Special Spaces". I've seen a lot of users on the Internet overrating the importance of the profiles selected for working spaces in the color settings believing that it plays a big role in every image being displayed while the fact is that it only affects the display of untagged images and does nothing to the files unless if set up to function as a conversion tool. I believe that the name of the "Working Spaces" section in the Color Setting adds to this misunderstanding.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: jc1 on October 06, 2011, 11:10:30 pm
Wonder why profile chosen for proof setup has the top priority? It is disable when a image file is read into PS.

When an image file is read into PS, do you agree that an working profile must be defined before further editing/viewing can be carried out?

jc
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 07, 2011, 12:39:35 am
Wonder why profile chosen for proof setup has the top priority? It is disable when a image file is read into PS.
Turning Soft proofing on and off does exactly the same as if choosing  Edit > Assign to another profile and when done, choose Edit > Assign > to the previous profile - just make sure you don't save before but after reassigning the original profile. So the next time you open the image it is displayed in the color space of the original  profile. Soft Proofing simply automates this process and also allows you to save in the middle of proofing without affecting the file.
Also soft proofing does the same what the profile selected for a working space in the color settings does to a untagged image, it just displays the image using the color space of the profile on the monitor but doesn't do anything to the file when saving it.
Information about soft proofing used is not saved with the file so when you open it again Photoshop can't automatically turn it on back for you and you have to do it manually.
When an image file is read into PS, do you agree that an working profile must be defined before further editing/viewing can be carried out?
If the image file is with a profile, the working profile in the color settings with default color management policy doesn't have any effect on the image and it will be displayed in the color space of the embedded profile. If the image is untagged (without a profile) then it will be displayed in the color space of the working profile. As I said this works the same as soft proofing, it it will not affect the color values in the file but only only in the video card for displaying it. The only difference from soft proofing is if you convert an untagged image to a profile - it will convert from the meaning of the colors as displayed in the color space of the working profile.
There is no rules when to changes the working profile in the color settings - it depends on what you want to do but in most cases people prefer to edit the image referring mostly to one color space and occasionally checking how the image looks in other color spaces using soft proofing. You may also make edits or alterations for a specific color space and separate the changes on different layers
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: fdisilvestro on October 07, 2011, 10:05:52 am
Turning Soft proofing on and off does exactly the same as if choosing  Edit > Assign to another profile and when done, choose Edit > Assign > to the previous profile


NO, soft proofing simulates "Convert to Profile", you can (should) also select the rendering intent when soft proofing. If Soft proofing did what you say, it would be completely useless.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 07, 2011, 10:45:46 am

NO, soft proofing simulates "Convert to Profile", you can (should) also select the rendering intent when soft proofing. If Soft proofing did what you say, it would be completely useless.
You are completely wrong and it will be completely useless if it does what you say. Soft Proofing as well as Assign Profile does not change the color values in the file but changes the appearance of the colors by altering the values the video card uses to show how the same values will be displayed in different color spaces.
Convert to Profile on the other hand changes the values in the file but doesn't change the values used by the video card to display the image which makes the image remains with the same appearance (no color change) but now the image is in another color space. And this is the whole idea behind color management to preserve the color appearance when reproducing the image in different color spaces by properly converting it. If soft proofing does the same as Convert to Profile you should see no difference and thus it will be useless.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: fdisilvestro on October 07, 2011, 11:04:02 am
If soft proofing does the same as Convert to Profile you should see no difference and thus it will be useless.

The reason you see diferences is because of different color gamuts between profiles (source - destination), white point, black point, and paper white (in case you select to simulate the paper white or paper color). Also the effect of the rendering intent is huge if your image has colors in the source profile that are out of the gamut of the destination profile. Selecting "perceptual" or "relative colorimetric" will make a lot of difference.

The advantage of using Soft Proofing is that you can edit in a well behaved working profile as ProphotoRGB or AdobeRGB and visualize the effect in your desired output profile (example, combination of printer and paper).

Just try to assign an output profile of an inkjet printer to an image and compare to soft proofing and you will convince yourself that soft proofing is not the same as Assign profile
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 07, 2011, 11:19:34 am
The reason you see diferences is because of different color gamuts between profiles ...
You are still getting it wrong, you should see a difference when Converting to profile only when the destination color space is narrower and only then the rendering intents make sense. When converting to a wider color space there will be no difference. Soft proofing does not simulate Convert to profile. The idea is actually very simple, take for example one color like pure red R=255, G=0, B=0. Display this color without changing its values on different monitors using the monitor's color space or print this color on various printers. The color produced using the same values will appear differently on all these various devices. Soft proofing simulates exactly that.
Convert to profile will change the RGB values to another value for each device to reproduce the same color appearance and for devices with narrower color spaces it will try to preserve the color appearance as much as possible.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: jbrembat on October 07, 2011, 11:23:02 am
Coloreason, you have to study color management.

Jacopo
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: fdisilvestro on October 07, 2011, 11:26:24 am
Coloreason,

It will depend on how you use Soft proofing. What you describe is the way it works when you select "Preserve RGB numbers" in the Soft proofing dialog.

IMHO this is not the usual way Soft Proofing is used by photographers.

Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 07, 2011, 12:03:00 pm
Coloreason,

It will depend on how you use Soft proofing. What you describe is the way it works when you select "Preserve RGB numbers" in the Soft proofing dialog.

IMHO this is not the usual way Soft Proofing is used by photographers.



Yeah, I was talking about soft proofing with Preserve RGB numbers. OK then, I stand corrected and agree with you about all what you said regarding soft proofing - it is useful to soft proof the conversion, so disregard all I said about comparing soft proofing to assign to profile or have in mind that comparison is valid only when Preserve RGB numbers is on. I apologize for the confusion and looking forward to discuss the other issues we've been talking about.

I really appreciate yours and everyone's input. :)
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 07, 2011, 12:38:49 pm
Yeah, I was talking about soft proofing with Preserve RGB numbers.

There is nearly zero reason to do this (for RGB). It can be useful for CMYK. Iíll not go into the reasons because this thread is getting a bit too deep and long winded.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 07, 2011, 02:30:54 pm
There is nearly zero reason to do this (for RGB). It can be useful for CMYK. Iíll not go into the reasons because this thread is getting a bit too deep and long winded.
;D Yeah the thread really got too long and winded but since you mentioned nearly zero reason with which I completely agree, I can't resist sharing the fact that I actually am using my soft proofing set to preserve RGB in the recent months working on a web project as a project manager and also being one of the designers. We're currently designing and developing a corporate web site where the use of color in images and html is important for the clients and we decided to calibrate and profile the monitors of the people in charge of approving the project who were in different office locations in town. Since we have wide gamut monitors, by using the monitor color profiles of the clients and soft proofing sRGB values with preserve RGB numbers turned on, we can have a good idea how sRGB images and html colors appear on different monitors used by the people responsible for approving the project. So there it is one of the 0.x reasons to use preserve RGB. I got used to using it this way recently that I forgot to realize that I'm rather a rare exception and gave not very appropriate comparison of soft proofing to Assign to Profile in my previous posts.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 07, 2011, 02:34:53 pm
Since we have wide gamut monitors, by using the monitor color profiles of the clients and soft proofing sRGB values with preserve RGB numbers turned on, we can have a good idea how sRGB images and html colors appear on different monitors used by the people responsible for approving the project.

Well certainly on your monitor. Others? Their mileage will vary (depending on browser).
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on October 07, 2011, 02:47:34 pm
There is nearly zero reason to do this (for RGB).

+1,
rare cases, for example in order to simulate a non-color-managed environment:
Proof Setup > Monitor RGB automatically enables Custom > Preserve RGB Numbers.
Possible source of confusion for some fellows.

Best regards, Peter

--
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 07, 2011, 02:49:03 pm
+1,
rare cases, for example in order to simulate a non-color-managed environment

On YOUR machine. Not others. Thatís hardly possible (without the other display, graphic path, profile). You can soft proof how ugly an image will appear using your non color manged appís or you coulds just load the document and look.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on October 07, 2011, 02:56:45 pm
On YOUR machine. Not others.

Yes,
I did not claim the opposite.

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Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 07, 2011, 03:41:38 pm
Well certainly on your monitor. Others? Their mileage will vary (depending on browser).
Right, having their monitor profiles and knowing what browser they use, we can only check how a certain group of people see the design with sRGB and html colors on their monitors and that was most important to us. We have no control over what the rest of the people on the internet will see.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on October 07, 2011, 04:09:53 pm
Right, having their monitor profiles and knowing what browser they use, we can only check how a certain group of people see the design with sRGB and html colors on their monitors and that was most important to us.

If I'm understanding the task correctly,
you have your images in sRGB, you have the monitor profiles of your client(s),
but what precisely do you do then in Photoshop ?

I think what the client(s) will see on their monitor (in a html non-color-managed environment) can not be simulated
with your computer, software and monitor when the monitor is different enough.

Monitor profiles are not only descriptive (e.g. regarding R/G/B primaries),
but also corrective (e.g. regarding R/G/B TRCs). So you finally need the device - the client's monitor, to see what comes out.

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Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 07, 2011, 06:49:08 pm
If I'm understanding the task correctly,
you have your images in sRGB, you have the monitor profiles of your client(s),
but what precisely do you do then in Photoshop ?...
I have the design as an sRGB image in Photoshop and soft proof it using client's monitor color profile with RGB numbers preserved.

I think what the client(s) will see on their monitor (in a html non-color-managed environment) can not be simulated
with your computer, software and monitor when the monitor is different enough.
A monitor color profile can be used in the same way as any other device color profile like printers for example. Photoshop can display how the image will be reproduced on the other device. Soft proofing with RGB numbers preserved, displays how the color values will be reproduced with the other device, and without RGB numbers preserved, displays how the converted values will be reproduced with the other device.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: MarkM on October 07, 2011, 08:06:18 pm
I have the design as an sRGB image in Photoshop and soft proof it using client's monitor color profile with RGB numbers preserved.
A monitor color profile can be used in the same way as any other device color profile like printers for example. Photoshop can display how the image will be reproduced on the other device. Soft proofing with RGB numbers preserved, displays how the color values will be reproduced with the other device, and without RGB numbers preserved, displays how the converted values will be reproduced with the other device.

This neither works in theory nor practice. I can attest to it not working in practice because I have two monitors side-by-side and just tried it. It's not even closeóin fact the match is much worse when I soft proof to the monitor profile.

In theory it doesn't work either. The part you are overlooking is that the RGB numbers get pumped through a video card with it's own LUT calibration curves that are set when you calibrate. They are normally in the profile in the vcgt tag, but they are ignored when you softproof.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: jc1 on October 07, 2011, 08:11:42 pm
I was talking about soft proofing with Preserve RGB numbers.

My understanding is that you were viewing an sRGB image with a wide gamut monitor, and soft proofing with sRGB profile. This is a special case in that when Preserve RGB is on, the soft proof RGB value is the same as sRGB value.
 
If the soft proofing target is an printer profile, when Preserve RGB is on, the soft proofing is showing the actual RGB value sent to the printer and that is not the normal way we soft proof the printer output.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 07, 2011, 08:18:12 pm
I have the design as an sRGB image in Photoshop and soft proof it using client's monitor color profile with RGB numbers preserved.

Having the clients profile, without the acutal display, and entire graphic system is useless. You have to have that client system to view what the client will see!
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: MarkM on October 07, 2011, 08:24:10 pm
Having the clients profile, without the acutal display, and entire graphic system is useless. You have to have that client system to view what the client will see!

While true, I can understand why people don't see this and why it's confusing. After all you don't need the client's printer and graphic system to softproof a printeróthis is a normal and useful thing to do. I find it really difficult to explain to people why monitors (and projectors) are different.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 07, 2011, 08:29:18 pm
While true, I can understand why people don't see this and why it's confusing. After all you don't need the client's printer and graphic system to softproof a printeróthis is a normal and useful thing to do. I find it really difficult to explain to people why monitors (and projectors) are different.

Its different because a soft proof isnít a print. If you want to see a print off the clients printer, you have to print it to that device. You could move that printer to another system and its a self contained process unlike a display system that uses a graphic system as part of the output process. Moving the printer and sending the same numbers will produce the same print from system A on system B. A soft proof isnít the same thing. When you try to soft proof another display on your display, thatís where things get dicy.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Peter_DL on October 07, 2011, 11:27:42 pm
In theory it doesn't work either. The part you are overlooking is that the RGB numbers get pumped through a video card with it's own LUT calibration curves that are set when you calibrate. They are normally in the profile in the vcgt tag, but they are ignored when you softproof.

Hmm,
further thinking about it,
Iím wondering if Coloreason could just profile the clientís monitor without calibrating it,
so that the resulting monitor profile is only "descriptive" while the video card loading part is left out.

Peter

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Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 08, 2011, 04:29:16 am
This neither works in theory nor practice. I can attest to it not working in practice because I have two monitors side-by-side and just tried it. It's not even closeóin fact the match is much worse when I soft proof to the monitor profile.

In theory it doesn't work either. The part you are overlooking is that the RGB numbers get pumped through a video card with it's own LUT calibration curves that are set when you calibrate. They are normally in the profile in the vcgt tag, but they are ignored when you softproof.
Thanks for bringing this up, I understand what you are saying and it makes sense. We didn't think about that. However we did make a test with multiple monitors in our studio and believed that this will work based on the result. We used wide gamut monitors to soft proof standard gamut monitors. The monitors we have are calibrated so well with the hardware controls that when the LUT loads during start up we don't see any noticeable difference. However I've seen a noticeable difference when the LUT loads  in the past with other monitors and this may be the cases with our clients monitors which I didn't calibrate personally but another designer from my team. I'm glad we started to talk about this, I will reevaluate the reliability of our workflow.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 08, 2011, 06:49:59 pm
Thinking about this, what happens in the following situation? Imagine an artist creating an artwork using a non-color managed program like one of the major 3D programs on a properly calibrated and profiled monitor but the artist dosent' have color managed programs like Photoshop. He sends his untagged artwork and his monitor profile to another person who uses another computer system with a color managed program, say Photoshop. Can the person with the color managed program recreate the colors as the 3D artist created them by assigning the received monitor profile to the received artwork?
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 08, 2011, 08:22:46 pm
Can the person with the color managed program recreate the colors as the 3D artist created them by assigning the received monitor profile to the received artwork?

In a color managed app, yes. But you could Assign and convert to a standardized color space like sRGB as well.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 08, 2011, 09:51:45 pm
In a color managed app, yes. But you could Assign and convert to a standardized color space like sRGB as well.
Thanks, then how about if the monitor profile received from the 3D artist is assigned to a random image in Photoshop for the purpose to show how the 3D artist should see it if displayed on his monitor? I'm struggling to understand how is this different from doing it to an image received from the 3D artist.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 09, 2011, 12:54:27 pm
Thanks, then how about if the monitor profile received from the 3D artist is assigned to a random image in Photoshop for the purpose to show how the 3D artist should see it if displayed on his monitor? I'm struggling to understand how is this different from doing it to an image received from the 3D artist.

I donít understand the question. If the user builds an image in a non color managed app, but has a display profile, after opening that image in Photoshop and assigning the display profile, the color appearance shodul be maintained. The numbers have an assocaited scale. Then convert to sRGB and hand off.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on October 09, 2011, 03:18:06 pm
Quote
Hmm,
further thinking about it,
Iím wondering if Coloreason could just profile the clientís monitor without calibrating it,
so that the resulting monitor profile is only "descriptive" while the video card loading part is left out.

Peter

Matrices that describe the colorants combined with the color temperature-(CT appearance varies between models and brands) work hand in glove with the vcgt RGB correction curves that maintain a linear distribution of 255 neutral gray tones between black and white.

All the slight bumbs, peaks and valleys you see in this RGB correction curve reduces and adds luminance to each 255 gray step to render a smooth gray gradient. Another display using only the matrices of the other display won't have these micro corrections that also affect the luminance of individual colors which acts on the preview similar to applying the same uneven curve to colors editing in Photoshop which I'm sure you've seen can affect the appearance of hue/saturation.

The matrices are only one leg of a three legged table of a display profile where not all colors are going to match between the two displays due to the other missing components that brings a display into a standard stable editing environment.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on October 09, 2011, 04:47:24 pm
Below is a diagrammed explanation of why soft proofing with another client's display profile won't work. Displays are messy places to edit if not calibrated and profiled which attempt to clean things up a bit. Only using the matrice part of the client's display profile and leaving out the vcgt correction curves won't tell the whole story of how that image should look especially if that image was edited on a display that accounted for the vcgt loaded in the video card.

And we're not including gamut shape differences on top of that.

Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 09, 2011, 11:19:46 pm
I donít understand the question. ...
I was expecting that the answer to my question in post #67 would be, "no" based on what I've been told in this thread that monitor profile is useless on any other display than the one it was made for. But you answered yes and I'm trying to understand this. If person A creates an image A in a non-color managed program on computer/monitor A and person B using computer/monitor B can recreate the colors of the image A by assigning the color profile of monitor A to the untagged image  then I wonder how is this different than when a random image X created on computer/monitor B and assigned the color profile of monitor A cannot recreate how the colors will be displayed on computer/monitor A.

Let me know if my question is still not clear, I'll try to say it in another way.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 09, 2011, 11:30:03 pm
Only using the matrice part of the client's display profile and leaving out the vcgt correction curves won't tell the whole story of how that image should look especially if that image was edited on a display that accounted for the vcgt loaded in the video card.

And we're not including gamut shape differences on top of that.


If it is not possible to create a color space describing how colors are displayed on a monitor by using a colorimeter and profiling software, I must have been with much higher expectation about what color management can do. I wonder if this is some sort of technical limitation or a matter of decision (user demand).
I guess they have to make 2 kinds of monitor profiles for a monitor, one for calibration and use for the current computer system and one that can be used on any other computer systems.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on October 10, 2011, 03:57:57 am
Quote
If it is not possible to create a color space describing how colors are displayed on a monitor by using a colorimeter and profiling software, I must have been with much higher expectation about what color management can do. I wonder if this is some sort of technical limitation or a matter of decision (user demand).
I guess they have to make 2 kinds of monitor profiles for a monitor, one for calibration and use for the current computer system and one that can be used on any other computer systems.

Didn't the diagram I posted above explain the two parts of a display profile?

There's no reason to use another display profile to show what images are suppose to look like on another calibrated/profiled display. The image will have the embedded profile/color space to make the image match on both displays. That's color management.

If your client isn't viewing tagged images on a calibrated/profiled display then the image isn't going to match anyway no matter what you do. It's that simple.

Even if you were to assign another display's profile containing the vcgt curves to the image as a way to soft proof, those curves would make the image look horrible because they are correcting for the anomalies of the other display that aren't present on the current monitor being soft proofed on. No two displays are exactly alike with regards to their calibration/vcgt correction curves.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 10, 2011, 09:46:35 am
Didn't the diagram I posted above explain the two parts of a display profile?
I understand there are two parts and I think I understand what they do but I still can't wrap my head around as to why monitors can't have profiles like printers for example. you send certain RGB value and it is displayed in a certain way. Knowing this why can't a color profile be created that can simulate the result without having the device?
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 10, 2011, 10:37:44 am
You are on system A using display A. Display profile from System B is useless in showing you what the user saw on that system (B).

Person on system A creates a document and EMBEDS display profile, the document maintains the color appearance seen on system A.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 10, 2011, 11:13:21 am
....
Person on system A creates a document and EMBEDS display profile, the document maintains the color appearance seen on system A.
To make sure I understand this. Is the following statement correct?
Person on system A creates a document and EMBEDS display profile, the document when displayed on any system maintains the color appearance as seen on system A
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 10, 2011, 11:30:51 am
To make sure I understand this. Is the following statement correct?
Person on system A creates a document and EMBEDS display profile, the document when displayed on any system maintains the color appearance as seen on system A
No

Not necessarily. Depends on the application used on the other systems, the condition (calibration) of the other systems. In an ICC aware app, with proper calibration, they should appear the same (within reason).
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 10, 2011, 12:44:25 pm
...
Not necessarily...
Yep, I know that. The question was "is it possible", in the context we were talking. So, it is, and I never thought otherwise but just wanted to confirm.
The thing that is confusing me is why this can work but not the other way around. If a monitor profile is telling only part of the truth how come it can tell the complete truth in this situation.

Or my confusion said in other words:
because of this: "You are on system A using display A. Display profile from System B is useless in showing you what the user saw on that system (B)."
then I don't understand why the monitor profile attached to an image can work in another situation when that vcgt tag is always disregarded.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: digitaldog on October 10, 2011, 02:25:51 pm
Lets try it this way. You are on a machine with a display that is calibrated and has a profile that defines that condition. You work in a non color managed app. The numbers are sent directly to the display (there is no understanding in this app of the color space, defined by a profile. There is no understanding of the display profile, its a non color managed app). This is how Photoshop worked prior to version 5. Your display was your editing space. What you see is what you get in this app, on this display (numbers sent to the display).

You move this document into Photoshop or other ICC aware application. Those applications need to understand two things. One is the color space of the numbers. Numbers without a color space are ambiguous. The appearance is based on the description of the numbers. That's why when you Assign a profile, you see the color appearance change but the numbers do not. The ICC aware application also needs to understand the display profile. With the working space (color space of associated numbers), and display profile, you can view the numbers correctly.

You have an untagged document from the 3D app. You assign the display profile in Photoshop to maintain the color appearance. Why? Because Photoshop now knows the scale of the numbers (display profile) AND uses the display profile to properly those numbers.

If you are on a system, with a calibrated display, that profile is unique to that system. It can't be transferred to another system, that system has its own display, graphic system, and profile. By assigning the display profile on the original system, the color appearance is maintained and then it be wise to convert to a well behaved working space like sRGB. You can provide that document to other ICC aware apps, on differing systems, those systems have their own display profile (not the original). The original display profile is only useful on the machine that made the document in the non color managed app.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on October 10, 2011, 02:34:25 pm
Quote
...then I don't understand why the monitor profile attached to an image can work in another situation when that vcgt tag is always disregarded.

By attached do you mean embedded, assign or converted to and embedded in the image? All of that can happen to an image regardless if it's sRGB/AdobeRGB/ProPhotoRGB and Monitor profile.

When you assign a display profile with vcgt curves to an image...(not sure if Windows systems yet attach vcgt to display profiles, it loads it at system startup, Macs do)...it changes the preview of the image to reflect all the bumps, hills and valleys seen in the RGB curves demonstrated above that corrects for the nonlinearity/nonuniform appearance of the display at the time of calibration/profiling of the other display. The current display proofing the image by assigning this other display profile to the image doesn't have the same bumps, hills and valleys in its RGB curves.

Some vcgt curves can be quite different display to display. See below:

http://photo.net/bboard-uploads//00HMf8-31289584.jpg

Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: MarkM on October 10, 2011, 10:18:40 pm
When you assign a display profile with vcgt curves to an image...it changes the preview of the image to reflect all the bumps, hills and valleys seen in the RGB curves demonstrated above that corrects for the nonlinearity/nonuniform appearance of the display at the time of calibration/profiling of the other display.

I don't think that's true. The vcgt curves can be embedded in a profile, but they are not part of the icc spec and they are generally disregarded in icc workflows. The only time I see them used is when I set a new profile for a monitor on the system level (Mac OSX). In that case the system reads the vcgt data from the profile and uploads it to the video card. After that they're forgotten about and I think photoshop rightly ignores them.

I've thought a bit about this over the last couple days and think I was wrong in my previous post (with some caveats) and think that colorreason's idea is not as far off the mark as we may think.

Consider this:

1. You have a sRGB image that is tagged and you are working in a profiled/calibrated environment. You send it to me, also in a calibrated environment. We can be pretty confident that we are seeing the same color appearance. Right? That's the point of color managementóeveryone is calibrated to a known standard and the image is tagged. We're goodóthis is the way it's supposed to work.

2. You convert that sRGB image to your monitor profile and send it to me. This is the same scenario as no. 1. The monitor profile might be different, but it is still a color profile built around a know standard. I can still convert from it to PCS, sRGB, or anything else. We'll still agree on a color framework.

3. You convert the sRGB image to your monitor profile and send it to me untagged, but with a copy of the monitor profile. I then apply the monitor profile and we are identical to No. 2.

4. You have untagged RGB data from a non-color-managed application on your profiled system. You can apply your monitor profile in a color managed app like photoshop without changing the color. You send this to me with your monitor profile. I also can apply your profile and we are back at No.3, which is the same as No. 2. Assuming your monitor profile accurately describes your monitor, I can apply the profile and we'll be speaking about the same color. This means that I can get a decent idea about what color looks like on your monitor in your non-color-aware apps with the caveats given below.

5. What you can't do: unplug your monitor and plug it into m video card using your profile. Unless my system behaves identically, we'll need to recalibrate and built a new profile.

Caveat: There will be some differences. We might have gamut issuesóyou might have a wide gamut monit that I clearly can't simulate on a normal monitor. I might be calibrated to a different white point and luminosity so the absolute colorimetric date may be different. Monitors next to each other may look different and may give different readings to a measurement device. But assuming that we account for what out eyes do with chromatic adaptation and such, we can be confident that the color appearance will be in the ballpark. Just because you are at 6500K and I'm at 5500K doesn't mean we can't agree on color.

The video card, vcgt problem is not as much of an issues as we might think because the profiles for the monitor are created after the vcgt has been uploaded to the card. We can think of the video card/monitor as one thing that we are profiling so long as we don't change them.

I've attached an unusual profile for an unusual monitor. You should be able to apply it to images and see what I'm seeing on this non-standard monitor.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Tim Lookingbill on October 11, 2011, 04:27:34 am
Quote
I don't think that's true. The vcgt curves can be embedded in a profile, but they are not part of the icc spec and they are generally disregarded in icc workflows. The only time I see them used is when I set a new profile for a monitor on the system level (Mac OSX). In that case the system reads the vcgt data from the profile and uploads it to the video card. After that they're forgotten about and I think photoshop rightly ignores them.

You're right, Mark. Brain fart!

I got all turned around trying to understand exactly Coloreason's points. This has been brought up several times I've been in discussions on this subject going back years and it never works.

I was cross remembering what happens when you load a custom display profile with vcgt curves from another display into the system not meant for that display which YOU DO see how off those vcgt curves makes the display.

There's still the issue with gamut shape matrice differences between the display your emulating by assigning that profile to the image and the color space the image is written and saved in such as  sRGB, AdobeRGB, etc. You'ld have to convert the image to the actual display being emulated but then you now can't assign that display in a Soft Proofing session.

I assigned your profile to the PDI color target and it turns it B&W. Neat trick. I understand your points but it seems to defeat the purpose of color management from an efficiency aspect. IOW it's too much of a PITA.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 13, 2011, 10:32:14 am
... the profiles for the monitor are created after the vcgt has been uploaded to the card. ...
That's the key here. This is how I always thought it works until people here started to mention the vcgt tag in relation to my workflow which made me think that this is not how it works. I thought that people mentioning vcgt tag are telling me that the profile is created before the calibration contribution of the video card (if talking about something else, I still have no idea what they were trying to tell me). If a monitor profile assigned to an image describes how colors will be displayed after adding a particular video card effect to a display (and not simply describing how a monitor displays colors)  then sending untagged image and a monitor profile to be assigned using another system should not work but I know for sure that this does work and everyone also agreed that works. Then if that works this means that the monitor profiles are created after the video card contribution to the calibration. And if this is the case then assigning the monitor profile to any image using a different system should show how the monitor for which the profile was created for will display the colors provided a wider gamut is used for the simulation.
...
Caveat: There will be some differences. We might have gamut issuesóyou might have a wide gamut monit that I clearly can't simulate on a normal monitor. I might be calibrated to a different white point and luminosity so the absolute colorimetric date may be different. Monitors next to each other may look different and may give different readings to a measurement device. But assuming that we account for what out eyes do with chromatic adaptation and such, we can be confident that the color appearance will be in the ballpark. Just because you are at 6500K and I'm at 5500K doesn't mean we can't agree on color...
The white point and luminosity will be taken into account and translated properly in the monitor simulation with assigning the profile to an image. If these are not translated properly then again, assigning a received monitor profile to received untagged image will not simulate the intended colors properly too and that's not the case as everyone agrees.
The practical limitation to this workflow is that because you want to soft proof the assignment (preserve RGB numbers) and not the conversion to the simulated monitor, the proofing monitor must be with wider gamut, otherwise this won't work - we tried that in our studio with soft proofing a standard gamut monitor using another standard gamut monitor and the result wasn't good.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: MarkM on October 13, 2011, 02:27:48 pm
The white point and luminosity will be taken into account and translated properly in the monitor simulation with assigning the profile to an image. If these are not translated properly then again, assigning a received monitor profile to received untagged image will not simulate the intended colors properly too and that's not the case as everyone agrees.

You should test this on two monitors with different white points.

This is how I understand it.

The white point should be all primaries at 100% -> [255, 255, 255]. If I send this to the monitor it should produce a color that corresponds to the the monitor's white point. If I assign a different monitor profile, even one with a different white point, the numbers are still [255, 255, 255]. When sent to the display, this color is then converted to my display via a relative colorimetric conversion, which means the white point is converted to the white point of the displaying monitor. Hence even if I assign a 5000K profile on my 6500K monitor, I will still see a 6500K white point. This is how is should beócolor appearances are preserved even though absolute colorimetric data is not. If you are looking at both monitors at the same time you will see different whites. But in most other cases, because your eyes will adapt to the different white point, it should look the same.

If it didn't work this way, you would see a white point shift when assigning a ProPhotoRGB(D50) profile to an AdobeRGB(D65) image, but you don't. The only way I know of to get a white point shift is to convert using absolute colorimetric intent and Apple's CMM engine.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Coloreason on October 14, 2011, 02:18:51 am
MarkM, I made some test by creating creating custom profiles with very different color temperature and primaries and what you said is completely correct, the different white points are mapped to the same appearance but it doesn't seem to be a big problem which initially made me think it is actually simulating the different white points.
I'm on Windows system which works similar to Adobe's and can't use Apple's engine.
Out of curiosity I tried assigning some of the others available RGB profiles that come with Photoshop and some of them like Fujifilm  3510 (RDI) Theater Preview (by Adobe) did change the white point. I guess it is some instructions in the profile that make absolute matching.

Thank you for your input, very much appreciated.
Title: Re: What's the point of using color spaces exceeding the visible spectrum?
Post by: Sheldon8 on October 14, 2011, 03:57:51 am
i would say to hold the colors.