marti.ma...@littlecms.com wrote: > > Hi Michel. > > If you use icctrans in such way, you are converting from sRGB (v4) > to the internal sRGB (v2), and a RGB value of (0, 0, 0) is correctly > converted to (0, 0, 0). > > You may way to inspect the PCS. icctrans shows teh v2 PCS > when using -v But then there are important differences between > V2 and V4. If you choose the output profile as a V2 identity, > you got: > > icctrans -t0 -i sRGB_v4_ICC_preference.icc -o*Lab > > Enter values, 'q' to quit > R (0..255)? 0 > G (0..255)? 0 > B (0..255)? 0 > > L*=0.0000 a*=0.0000 b*=0.0000 > > If you use a V4 Lab identity: > > icctrans -t0 -i sRGB_v4_ICC_preference.icc -o*Lab4 > Enter values, 'q' to quit > R (0..255)? 0 > G (0..255)? 0 > B (0..255)? 0 > > L*=3.1112 a*=0.0000 b*=0.0000 > > Is that the effect you were expecting? >
Ahh yes, certainly. Thanks for clarifying that. Previously I assumed, that with -v option and as long as I'm interested in PCS values only, the -o profile didn't really matter - so from what I understand, icctrans will try to compensate for user errors (as above, when mixing v2 and v4 perceptual intents) and present expected (from perspective of destination profile) PCS values ? > Otherwise a RGB of (30, 30, 30) is converted by PhotoshopCS4 to > Lab=(11, 0, 0) which is the same as lcms did. > Nevermind that, I think I underestimated effects of mixing black point scaled and unscaled profiles (and forgot about post-gamma influence in PCS). Thanks for your help. ------------------------------------------------------------------------------ Register Now for Creativity and Technology (CaT), June 3rd, NYC. CaT is a gathering of tech-side developers & brand creativity professionals. Meet the minds behind Google Creative Lab, Visual Complexity, Processing, & iPhoneDevCamp asthey present alongside digital heavyweights like Barbarian Group, R/GA, & Big Spaceship. http://www.creativitycat.com _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
