Variations in Color Engines, Adobe ACE, Microsoft ICM, ARGYLL, and Matlab

[Doug Gray]

Since you are trying to investigate such low level effects, what white points do each of your tested methods use?  What about Lab<->XYZ conversion formulas?  How is chromatic adaptation performed?  Also, do any of these use FP vs Integer math internally?

E.g. This is D50's White Point in XYZ as specified by ICC [31595  32768  27030]/32768 = [96.4203  100.0000   82.4890].  Bruce Lindbloom says [96.4220   100.0000   82.5210].  dE is 0.0260.

Jack

Yup. I changed the synthetic AdobeRGB printer profile to scale the WP to the MP101 matte paper. Then I made  Argyll and I1Profiles and checked the AtoB results over a random rgb set. Average dE was .23 which is way above roundoff error or the small discrepancies n D50 between CIE and ICC.

That is the sort of error I would expect if the Wrong_Vonkries global setting wasn't working. It's still fairly small but that's because I'm using M2 measurements for the paper scans. My error. I was using this:

SET ARGYLL_CREATE_WRONG_VON_KRIES_OUTPUT_CLASS_REL_WP

and I should have been using this:

SET ARGYLL_CREATE_WRONG_VON_KRIES_OUTPUT_CLASS_REL_WP=1

This was a major problem as it caused slightly greater error in Argyll v I1Profiler.  It would have been more obvious had I been using M0 or M1.

[Jack Hogan]

Yup. I changed the synthetic AdobeRGB printer profile to scale the WP to the MP101 matte paper. Then I made  Argyll and I1Profiles and checked the AtoB results over a random rgb set. Average dE was .23 which is way above roundoff error or the small discrepancies n D50 between CIE and ICC.

That is the sort of error I would expect if the Wrong_Vonkries global setting wasn't working. It's still fairly small but that's because I'm using M2 measurements for the paper scans. My error. I was using this:

SET ARGYLL_CREATE_WRONG_VON_KRIES_OUTPUT_CLASS_REL_WP

and I should have been using this:

SET ARGYLL_CREATE_WRONG_VON_KRIES_OUTPUT_CLASS_REL_WP=1

This was a major problem as it caused slightly greater error in Argyll v I1Profiler.  It would have been more obvious had I been using M0 or M1.

Interesting.  I am not very familiar with Argyll.  Are Argyll, ICM, ACE all using the same wavelength/M-weight range to compute the white point?

[Doug Gray]

Interesting.  I am not very familiar with Argyll.  Are Argyll, ICM, ACE all using the same wavelength/M-weight range to compute the white point?

Argyll is a nice collection of open source color management tools by Graeme.

https://argyllcms.com/

When comparing different tools I only use RGB/LAB(at D50) pairs. There are subtleties like interdevice variations, etc. when including spectral data and it's best to avoid them unless a good reason to stray from D50 exists.

Adobe ACE, like other CMEs, don't use spectral data. It's not part of ICC profiles except for the most recent, post V4 which is pretty nascent.

[MfAlab]

Adobe ACE, like other CMEs, don't use spectral data. It's not part of ICC profiles except for the most recent, post V4 which is pretty nascent.

It's a great job you've done. Thanks for sharing.

Spectral data color engine only available in limited software. ONYX(it's a RIP) is one of them. The new version support iccMAX rendering and building. iccMAX is called ICC V5 or ICC2. It has the ability to use spectral data and supports spectral PCS. Better than ICC V4 which use a fixed D50 PCS. It's mainly develop by Max Derhak, Co-Chair of ICC and also principal scientist of ONYX. That's why ONYX is the first RIP to support iccMAX. Don't know when will Adobe support it.

iccMAX page in ICC website
official open source implementation on GitHub