Hi Andrea This is correct. CIE L*a*b* is independent of white point in relative colorimetric intent or ICC-Absolute. Only when you use V2-Absolute it makes a difference. It has a sort of "wrong-von-kries" chromatic adaptation embedded in the model.
C:\lcms2-2.1\bin>transicc -t3 -d0 -i*Labd65 LittleCMS ColorSpace conversion calculator - 4.2 [LittleCMS 2.05] Enter values, 'q' to quit L*? 50 a*? 0 b*? 50 R=135.8546 G=117.6456 B=22.3588 Enter values, 'q' to quit L*? q Done. C:\lcms2-2.1\bin>transicc -t3 -d0 -i*Lab LittleCMS ColorSpace conversion calculator - 4.2 [LittleCMS 2.05] Enter values, 'q' to quit L*? 50 a*? 0 b*? 50 R=144.0772 G=115.9433 B=1.9909 Regards Marti El 09/04/2013 18:30, Andrea Galligani escribió: > Hi, > > I tested the creation and use of a Lab profile with different white points. > > I tried transicc by using the default illuminant in the following way: > > transicc -i*Lab > LittleCMS ColorSpace conversion calculator - 4.2 [LittleCMS 2.04] > > Enter values, 'q' to quit > L*? 50 > a*? 0 > b*? 50 > > R=135.1773 G=116.7732 B=14.9372 > > Then I tried transicc by using the D65 illuminant and I got this > > transicc -i*LabD65 > LittleCMS ColorSpace conversion calculator - 4.2 [LittleCMS 2.04] > > Enter values, 'q' to quit > L*? 50 > a*? 0 > b*? 50 > > R=135.1773 G=116.7732 B=14.9372 > > Is this correct? > > I also tried tificc by translating a 16-bit Lab image to sRGB using this > command lines: > > tificc -i*Lab MyLabImage.tif D50.tif > tificc -i*LabD65 MyLabImage.tif D65.tif > > but comparing D50.tif and D65.tif are identical. (I used a binary-file > compare utility) > > I've done something wrong or there is a bug somewhere? > > Thanks a lot > Andrea > > > ------------------------------------------------------------------------------ > Precog is a next-generation analytics platform capable of advanced > analytics on semi-structured data. The platform includes APIs for building > apps and a phenomenal toolset for data science. Developers can use > our toolset for easy data analysis & visualization. Get a free account! > http://www2.precog.com/precogplatform/slashdotnewsletter > _______________________________________________ > Lcms-user mailing list > Lcms-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/lcms-user > ------------------------------------------------------------------------------ Precog is a next-generation analytics platform capable of advanced analytics on semi-structured data. The platform includes APIs for building apps and a phenomenal toolset for data science. Developers can use our toolset for easy data analysis & visualization. Get a free account! http://www2.precog.com/precogplatform/slashdotnewsletter _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
