Hi Mark, That's black point compensation, V4 perceptual and saturation have non-zero black points. sRGB built-in is basically a V2 profile, so for going from V2 black (which is zero) to v4 black (which is about L*=3) we need some sort of scaling.
Regards Marti Quoting Mark <d...@cine-scan.com>: > Hi Marti > > looking at the stages created for a sRGB -> XYZ transform I see 3 > stages are generated > - curve set stage for the gamma curves > - matrix float stage converting device rgb to xyz (I see the matrix > is scaled so by 1/MAX_ENCODEABLE_XYZ) > - a second matrix including offset: > Offset: 0.0016800256 0.0017365765 0.0014350219 > Matrix: 0.9965152458 0.0000000000 0.0000000000 > 0.0000000000 0.9965269000 0.0000000000 > 0.0000000000 0.0000000000 0.9965207904 > > Can you tell me what the second matrix stage does? > The matrix varies according to the intent passed creating the > transform. The data above is for INTENT_PERCEPTUAL and > INTENT_SATURATION (IIRC). > INTENT_ABSOLUTE_COLORIMETRIC uses other values, without offset. > INTENT_RELATIVE_COLORIMETRIC does not have this second matrix stage. > > Best regards > Mark > ------------------------------------------------------------------------------ > ThinkGeek and WIRED's GeekDad team up for the Ultimate > GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the > lucky parental unit. See the prize list and enter to win: > http://p.sf.net/sfu/thinkgeek-promo > _______________________________________________ > Lcms-user mailing list > Lcms-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/lcms-user > ------------------------------------------------------------------------------ ThinkGeek and WIRED's GeekDad team up for the Ultimate GeekDad Father's Day Giveaway. ONE MASSIVE PRIZE to the lucky parental unit. See the prize list and enter to win: http://p.sf.net/sfu/thinkgeek-promo _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
