besides the cases already covered with gamut mapping etc, you can also get "negative" values due to uncertainty of where black is. Take for example the case of a digital sensor in a camera, if you capture with the lens cap on, noise will mean you will get a range of values about a mean value, if this is value considered as 0 then there will be some pixels where the value is less than zero, throwing away this by clipping degrades the quality of the images.
on the subject of extending/extrapolating trc, one approach is to mirror the function similar to Elle's suggestion using temp = pow(abs(x)) out = copysign(temp, x) this tends to be reasonable as it gives a continuous gradient. Kevin ------------------------------------------------------------------------------ _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
