On Tue, 26 May 2015, marti.ma...@littlecms.com wrote: > > > Oh, I see... You profile forces L* to zero but keeps a* and b*, > > Right, the interpretation on what something like Lab (0, 10, 20) means, is up > to the output profile. > Hint: L*=0 does not always map to sRGB=(0,0,0). Try transicc or Photoshop: > > transicc.exe -i*Lab -o*sRGB > LittleCMS ColorSpace conversion calculator - 4.3 [LittleCMS 2.08] > > Enter values, 'q' to quit > L*? 0 > a*? 10 > b*? 20 > > R=29.9669 G=-9.1523 B=-48.4744 > > Here you got a lot of red from L*=0, and this is mathematically correct. Do > the math by hand if you are not convinced.
Well... I was afraid that that would be the reason. But it means that we cannot use the recipe in https://www.mail-archive.com/lcms-user@lists.sourceforge.net/msg01509.html to create a brightness/contrast filter that works the way our users expect, so we need to figure out something new... I guess it would be cheating to check the lightness curve for being all zero or all ffff and if so, just mean the whole image white or black :-) Boudewijn ------------------------------------------------------------------------------ _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
