Hi Florian, You are right. It seems I did a mistake when fixing a previous bug in the absolute colorimetric intent. I have uploaded to GIT repository a fix, but I'm still testing, as I'm not 100% sure this code covers properly all the cases.
Thanks for reporting Best regards Marti Original Message: ----------------- From: Florian Höch lists+lcms-u...@hoech.org Date: Sun, 07 Aug 2011 15:53:33 +0200 To: lcms-user@lists.sourceforge.net Subject: [Lcms-user] LCMS 2.2: Possible bug incmsvirt.c/cmsCreateRGBProfileTHR, 'chad' converts from PCS to device Hi, I think there may be a bug in cmsvirt.c/cmsCreateRGBProfileTHR, in the call to _cmsAdaptationMatrix, which causes the 'chad' matrix from resulting profiles to convert from PCS to device instead of the other way around. (From the ICC spec) "This tag, which must be invertible, converts an XYZ colour, measured at a device's specific illumination conditions, to an XYZ colour in the PCS illumination conditions after complete adaptation." So, the inverted matrix should do the opposite. This is not the case with the profile I looked at. When I multiply the inverted matrix with D50 XYZ numbers, which should yield the device illuminant (CCT around 6460K), I get a far too 'warm' result (CCT around 4408K). Not inverting the matrix yields the correct values. I think the FromIll/ToIll arguments to _cmsAdaptationMatrix are simply reversed. _cmsAdaptationMatrix(&CHAD, NULL, cmsD50_XYZ(), &WhitePointXYZ); should probably be: _cmsAdaptationMatrix(&CHAD, NULL, &WhitePointXYZ, cmsD50_XYZ()); Regards -- Florian Höch ---------------------------------------------------------------------------- -- BlackBerry® DevCon Americas, Oct. 18-20, San Francisco, CA The must-attend event for mobile developers. Connect with experts. Get tools for creating Super Apps. See the latest technologies. Sessions, hands-on labs, demos & much more. Register early & save! http://p.sf.net/sfu/rim-blackberry-1 _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user -------------------------------------------------------------------- mail2web LIVE Free email based on Microsoft® Exchange technology - http://link.mail2web.com/LIVE ------------------------------------------------------------------------------ BlackBerry® DevCon Americas, Oct. 18-20, San Francisco, CA The must-attend event for mobile developers. Connect with experts. Get tools for creating Super Apps. See the latest technologies. Sessions, hands-on labs, demos & much more. Register early & save! http://p.sf.net/sfu/rim-blackberry-1 _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
