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Author Topic: attention color whizes: non-typical sRGB/RGB/ProPhoto question  (Read 222072 times)

Graystar

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #620 on: January 09, 2011, 12:17:07 pm »

With Absolute Colorimetric, the white points are different and a portion of Adobe RGB is outside the gamut of ProPhoto RGB as Joofa has maintained.

No. Please see the chart in my post here...
http://www.luminous-landscape.com/forum/index.php?topic=49940.msg414096#msg414096

It is Absolute.  You can see the different white points.  Adobe RGB is inside of Pro Photo.  It is Gamutvision.  It is not flaky...it gives the same correct results everytime.
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tgray

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #621 on: January 09, 2011, 12:27:41 pm »

> It does seem to me that joofa has a point, but it's most likely not relevant for everyday use.

If you look at how proofing is done absolute colorimetric intent is in use there for certain cases. The goal of proofing is to mimic behavior of one media using a different media. Consider the real life scene to be presented to the eye observing it in person as one media, and the presentation of that scene on a display or on a print as the other media. Now what are we going to use as the rendering intent if we want to recreate the original impression of the scene?

Agreed.  That was brought up by Mark I think.  Though it would surprise me if you had an image in AdobeRGB and you were proofing in Prophoto RGB for output onto media.
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Iliah

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #622 on: January 09, 2011, 12:35:14 pm »

> Though it would surprise me if you had an image in AdobeRGB and you were proofing in Prophoto RGB for output onto media.

To me, these two colour spaces are just an example why it is important to be careful using chromatic adaptation. However printer manufactures strive to cover ProPhoto while many photographed scenes fit nicely into smaller spaces. The reverse situation is not well-solved using perceptual intent as well, not to mention currently support for this intent in matrix profiles is extremely limited and visually problematic.
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digitaldog

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #623 on: January 09, 2011, 12:38:10 pm »


Interesting article by (Prof.) Gernot Hoffmann,
page 4 also expands on "chromatic adaptation is not perfect":

I don’t think the proponents of using chromatic adaptation to illustrate how these two color spaces in question, and their resulting gamuts appear, have suggested that it is perfect. The argument is its necessary, when using said profiles for color space conversions, imperfect or close to perfect. The proponents of “don’t use chromatic adaptation” to produce a gamut map that enforces their beliefs have not on the other hand, told us when, where, how or why we would not use the adaptation, imperfect or not. Bruce clearly points this out in his post as I read it.
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digitaldog

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #624 on: January 09, 2011, 12:42:37 pm »

> It does seem to me that joofa has a point, but it's most likely not relevant for everyday use.

If you look at how proofing is done absolute colorimetric intent is in use there for certain cases. The goal of proofing is to mimic behavior of one media using a different media. Consider the real life scene to be presented to the eye observing it in person as one media, and the presentation of that scene on a display or on a print as the other media. Now what are we going to use as the rendering intent if we want to recreate the original impression of the scene?

But such proofing conversations are using a true output profile to map the paper white. The two profiles in question are theoretical display profiles as I think was pointed out somewhere in this long set of posts (by Bruce perhaps?). They were designed for a purpose and to be well behaved when making conversions (R=G=B=neutral). Also discussed and demonstrated was the so called clipping (or lack thereof) when using these two profiles with both a RelCol and AbsCol intent. IOW, using proofing in this context with other, LUT based profiles is IMHO OT to the gamut theories proposed here.
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Iliah

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #625 on: January 09, 2011, 12:45:25 pm »

No. Please see the chart in my post here...
http://www.luminous-landscape.com/forum/index.php?topic=49940.msg414096#msg414096

It is Absolute.  You can see the different white points.  Adobe RGB is inside of Pro Photo.  It is Gamutvision.  It is not flaky...it gives the same correct results everytime.

Hm. I asked you to show the steps you've used to come up with the plot. Attached is a 3D wrl plot made using absolute colorimetric intent and CIECAM02 "original scene - bright outdoors" viewing conditions. AdobeRGB is in white, ProPhotoRGB is in "natural colour".
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Iliah

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #626 on: January 09, 2011, 12:52:44 pm »

So-called camera profiles are often matrix-based (sometimes even those that pretend to be LUT-based); display profiles are often matrix-based too. We have what we have.
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Peter_DL

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #627 on: January 09, 2011, 01:23:31 pm »

Interesting article by (Prof.) Gernot Hoffmann,
page 4 also expands on "chromatic adaptation is not perfect":

http://www.fho-emden.de/~hoffmann/cmsicc08102003.pdf
--

Maybe I should have added a couple of further lines to the example reported earlier:

>> Example: some years ago I had problems with monitor calibration & profiling. Suddenly all images looked greenish to me (in a color-managed environment). Actually I was not really able to adapt to the new white point of my monitor. I didn't like it. It should have been unchanged D65, but that was obviously not the case anymore. In order to verify my impression I created a white patch, assigned my monitor profile and converted AbsCol to a D65 working space. The result was that R, G, B got different from each other, confirming that my monitor white wasn't D65. The rest turned out to be a handling error with the software package.<<

But for a couple of days, before getting my monitor back to 'normal' and a believable white, I simply installed a fix Proof, AbsCol, D65 working space to monitor profile. That worked well enough.

This was in times of Photoshop CS when Adobe’s CMM supported AbsCol rendering between matrix spaces. Not sure why it was dropped. Could be an interesting question on its own. Today we need to resort to Microsoft’s CMM. For example, to illustrate that some Abobe RGB colors are outside ProPhoto RGB in an abscol sense:




Screenshot of a Granger Rainbow in Adobe RGB
Customized Proof Setup to ProPhoto RGB, AbsCol rendering
Gamut warning enabled, Conversion Engine: Microsoft ICM
Photoshop CS4 on Windows (should work with Apple’s CMM as well, and was also given with Adobe’s ACE in former Photoshop CS).
Corresponds to some of the 3D plots at least which we have seen here...

When you compare the gamuts AdobeRGB (white) and ProPhoto (wireframe) abscol in relation to D50…:
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Graystar

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #628 on: January 09, 2011, 02:00:20 pm »

Hm. I asked you to show the steps you've used to come up with the plot.

As Joofa has suggested, you can Google that information.  It is easy to find and proves that Adobe RGB is completely inside of Pro Photo.  I can't overemphasize that fact.
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Iliah

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #629 on: January 09, 2011, 03:19:36 pm »

>> Hm. I asked you to show the steps you've used to come up with the plot.
> As Joofa has suggested, you can Google that information.

Your report on how you used GamutVision is not in Google.
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tho_mas

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #630 on: January 09, 2011, 05:31:47 pm »

No. Please see the chart in my post here...
http://www.luminous-landscape.com/forum/index.php?topic=49940.msg414096#msg414096

It is Absolute.  You can see the different white points.  Adobe RGB is inside of Pro Photo.  It is Gamutvision.  It is not flaky...it gives the same correct results everytime.
I think there are 2 steps involved in your graph.
The "white" of AdobeRGB is spinned towards yellow and the whole thing is displayed under D50 conditions.
Displaying a comparison of both the colours spaces under their own respective lighing conditions is different.

The latter looks like this (the same as my graphs above and those of bjanes and Iliah)





Your image looks like ProPhoto abscol converted to AdobeRGB and displayed relcol to D50 (i.e. to ProPhoto).

Now, with my tools (Color Think standard) I can't replicate your graph, but there's a workaround.
I assigned ProPhotoRGB to the Granger Rainbow. The image loaded in the grapher shows exactly the shape of the ProPhoto icc profile (of course) as you can see here (white = icc profile / dots = image):


I've converted this image (i.e. the Granger Rainbow in ProPhoto) abscol to AdobeRGB.
I can't switch the RI in the Standard version of Color Think's grapher so I've converted the image back to ProPhoto (relcol).
This way I am able to compare it to ProPhoto in the grapher.
This is the result… and it seems that is exactly what your grapher is showing:


the same from a different angle:



I don't know the correct terminology to describe what your graph shows… but it doesn't show the 2 profiles under their respective white points.
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tho_mas

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #631 on: January 09, 2011, 05:38:50 pm »

This was in times of Photoshop CS when Adobe’s CMM supported AbsCol rendering between matrix spaces. Not sure why it was dropped.
I think we should make a difference between "ACE" and "Adobe CMM". These are different CMMs (see attachment).
Only the built in engine doesn't perform abscol in conjunction with matrix profiles as target whereas "Adobe CMM" does.

« Last Edit: January 09, 2011, 05:41:12 pm by tho_mas »
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digitaldog

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #632 on: January 09, 2011, 06:18:15 pm »

Now, with my tools (Color Think standard) I can't replicate your graph, but there's a workaround.

This link may explain why your copy of ColorThink Standard doesn’t replicate this and why my copy of ColorThink Pro does:
http://lists.apple.com/archives/colorsync-users/2006/Jun/msg00235.html
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jeremypayne

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #633 on: January 09, 2011, 06:23:51 pm »

This link may explain why your copy of ColorThink Standard doesn’t replicate this and why my copy of ColorThink Pro does:
http://lists.apple.com/archives/colorsync-users/2006/Jun/msg00235.html

"I'm sure it will create some discussion along the way..."

That's an understatement!!  :D

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tho_mas

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #634 on: January 09, 2011, 06:32:25 pm »

This link may explain why your copy of ColorThink Standard doesn’t replicate this and why my copy of ColorThink Pro does:
http://lists.apple.com/archives/colorsync-users/2006/Jun/msg00235.html
I am not sure if I understand correctly:
do you mean "new" Color Think displays the same as "Graystar's" graph from Gamutvision when the RI is set to abscol? So "bjanes" abscol graph shown above (which is the same as mine) is also made with an "old" Color Think version?
So with the RI set to "abscol" is AdobeRGB displayed like this: http://www5.pic-upload.de/07.01.11/gnhzegyold.jpg ...
or is AdobeRGB displayed like this: http://www6.pic-upload.de/09.01.11/bebefrcuxmeq.jpg ?
Or do you simply mean Color Think Pro can switch RI's?

The contribution of Steve Upton is from June 2006. I am using CT 2.2.1b5 released October 2009.
The grapher still displays abscol in relation to D50.
« Last Edit: January 09, 2011, 06:38:11 pm by tho_mas »
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MarkM

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #635 on: January 09, 2011, 06:44:21 pm »

I am not sure if I understand correctly:
do you mean "new" Color Think displays the same as "Graystar's" graph from Gamutvision when the RI is set to abscol? So "bjanes" abscol graph shown above (which is the same as mine) is also made with an "old" Color Think version?
So with the RI set to "abscol" is AdobeRGB displayed like this: http://www5.pic-upload.de/07.01.11/gnhzegyold.jpg ...
or is AdobeRGB displayed like this: http://www6.pic-upload.de/09.01.11/bebefrcuxmeq.jpg ?
Or do you simply mean Color Think Pro can switch RI's?

The contribution of Steve Upton is from June 2006. I am using CT 2.2.1b5 released October 2009.
The grapher still displays abscol in relation to D50.


ColorThink Pro 3 can switch rendering intents. You can get both results.
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digitaldog

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #636 on: January 09, 2011, 06:44:25 pm »

ColorThink Pro’s default for mapping is a radio button called Device Gamut (which produces the map the same as setting RelCol). There is another radio button option to pick specific rendering intents, in this context, the selection of Abs will produce a graph that pushes the blue of Adobe RGB outside the gamut of ProPhoto RGB. I don’t know what the defaults for Non Pro are, but what Steve is saying in my mind confirms what Bruce has said as well. The need for adaptation and how (by default and text below), the gamuts should be viewed. Keep in mind here, the two profiles in question here are considered “monitor” profiles.

Quote
- to the "adapted eye" each monitor would appear to have a "white" white point and all colors would fall out relative to that white. So to the adapted eye the white points should line up.

- it turns out that any white point other than D50 in monitor profiles was not intended in v2 profiles and has been "outlawed" in v4 profiles. All colors are to be adapted to D50 and the white point should be D50 from now on.

- gamut comparisons should be done with the white points adapted in some manner. This will give a better indication of how two gamuts compare that when one of them has a shifted white point.

With this is mind it makes more sense to map all monitor gamuts to 100,0,0 which is how ColorThink Pro now plots and non-pro ColorThink will follow as well.
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tho_mas

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #637 on: January 09, 2011, 06:55:09 pm »

ColorThink Pro 3 can switch rendering intents. You can get both results.

ColorThink Pro’s default for mapping is a radio button called Device Gamut (which produces the map the same as setting RelCol).

you guys didn't read my post or you did not understand "Graystar's" graph.
"Graystar's" graph is supposed to show ProPhoto and AdobeRGB abscol.
But it's completey different from Color Think's abscol graph (IMO CT's graph is correct).
This is CT abscol: http://www5.pic-upload.de/07.01.11/gnhzegyold.jpg
But this is not CT relcol: http://www6.pic-upload.de/09.01.11/bebefrcuxmeq.jpg
but the latter is... most likely... what "Graystar's" grapher shows: http://home.roadrunner.com/~graystar/adobergb-prophoto.jpg
Whereas relcol is like in Bruce Lindblooms grapher (or Color Sync utility).

Quote
I don’t know what the defaults for Non Pro are
well, as I said: abscol

Quote
what Steve is saying in my mind confirms what Bruce has said as well. The need for adaptation and how (by default and text below), the gamuts should be viewed.
sure, but that is a different question.
My post above was meant to replicate "Graystar's" graph ... and you can't replicate it in ColorThink... neither when you set the RI to recol or abscol. "Graystar's" graph from Gamutvision involves at least two transforms. That's what my post is about.
« Last Edit: January 09, 2011, 07:22:17 pm by tho_mas »
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digitaldog

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #638 on: January 09, 2011, 07:10:51 pm »

It appears Gamutvision is a Windows only product, so I can’t comment on it specifically. I can’t comment on why the MS CMM does stuff that the Adobe CMM doesn’t either but if given an option for what to use for conversions, it be ACE. I’ll dig up the old X-Rite (GamutWorks) grapher and see what it provides.
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tho_mas

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Re: attention color whizes: non-typical sRGB/RGB/ProPhoto question
« Reply #639 on: January 09, 2011, 07:17:35 pm »

It appears Gamutvision is a Windows only product, so I can’t comment on it specifically.
in my opinion it shows something that is definitely not abscol and definitely not relcol.
abscol would show blues/cyans/magentas and white outside of ProPhoto. And relcol would equalize the white points (as in Br. Lindbloom's grapher). This is why I think the graph shows two transformations simultaneously.

Quote
I can’t comment on why the MS CMM does stuff that the Adobe CMM doesn’t either but if given an option for what to use for conversions, it be ACE.
well, as I have mentioned several times: "Adobe CMM" does perform abscol with matrix profiles. Other than that it's exactly the same as "ACE".
"ACE" doesn't provide abscol with matrix profiles as target anymore... most likely to avoid "user errors" or so. But at the same time they trashed the option to use abscol intentionally.
You may download "AdobeCMM" here and play around with it a bit: http://www.adobe.com/support/downloads/detail.jsp?ftpID=3617

« Last Edit: January 09, 2011, 07:20:35 pm by tho_mas »
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