Elena [service address] wrote:
Graeme, are you sure isn't there some subtle bug you never noticed ? How is that clipped out of gamut colors cause a so big waste of time and resources ?
Because clipping properly is hard. You have to locate the closest point on the gamut surface. I have used many acceleration techniques in the code, and it is a great deal faster in this area than it once was. You can use memory to reduce the size of the acceleration lists it has to look for, but setting the ARGYLL_REV_ACC_GRID_RES_MULT environment value.
If so, then think what happens with colprof: even using -ip there are LOTS (the majority ?) of points in the Lab/XYZ B2A table corresponding to clipped colors slowing down things terribly - since the source gamut used for gamut mapping will NEVER cover the entire Lab/XYZ space! Points that after all will never be used, possibly... If I'm reasoning correctly, of course...
For colorimetric, the "source" gamut is the ICC L*a*b* cube. The colorimetric B2A has to map every point in that cube to the colorimetrically closest in gamut value. Graeme Gill.