Gerhard Fuernkranz <[EMAIL PROTECTED]> said: > > > How do you actually intend to distinguish and handle the two different > kinds of V2 profiles? > > 1. the V2 profiles which behave like the sRGB 1998 profile,
See my paper here: http://www.littlecms.com/Absolute%20colorimetric%20intent1.pdf Basically, if a v2 profile is a display profile then media white tag refers to display white point, so virtual media white is assumed as perfect diffuser of D50 and a virtual CHAD is computed assuming Bradford transform from whatever illuminant stated in media white tag to D50. I am guessing here that chromatic adaptation used is Bradford, I think this is reasonable. After that, all absolute intents are computed by using the CHAD tag if adaptation state = 0 (unadapted) or without CHAD if adaptation state = 1 (fully adapted). This seems to cover all cases. v2 having D65, for example, would be reduced to D50 as media white + a CHAD from D50 to D65. v2 Printer profiles are not affected. > 2. the V2 profiles which behave "as it was ever intended > by the ICC" (i.e. with wtpt tag adapted to PCS illuminant) Any v2 using D50 as media white would exhibit identical results for rel.colorimetric and abs.colorimetric, since CHAD would result in an identity matrix. Just as expected initially. > And what about V2 profiles with "chad" tag (introduced with profile > version 2.4)? Is it safe to generally assume, that they behave like V4 > ones? For instance, what about the new 2004 srGB profiles (which have a > "chad" tag, though the header actually sais profile version 2.0)? Will also work. Those profiles are working in lcms 1.14, in fact I'm using the CHAD independently of version, just because I found many profiles with such tag and wrongly labeled as v2. Regards, Marti. ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
