Yaron Tadmor wrote: > For some reason I assumed the PCS's are general enough to do all > blending properly, but that could be due to some conceptual > misunderstanding of color spaces, profile and/or blending.
Blending is what you define it to be. The closest thing to a "natural" blend is to emulate light interactions, which means doing computation in a linear light space. Many systems don't bother with this, and use blending on gamma encoded space (ie. typical device dependent RGB), and end up with a different result to a natural blend. Blending in L*a*b* space or CMYK will give you quite different results again. L*a*b* is an approximately perceptual space, so it is far from linear light, and in fact is different from device spaces in that a* and b* encode hue and saturation independently to luminance. CMYK will give you odd results with some combinations, because it has a redundant dimension, meaning that for any particular color there are many possible CMYK combinations could encode that color, each one having a different K value. You could in CMYK space blend two CMYK values that represent the same color, and end up with a different color - the locus of CMYK value for a single color is not necessarily a straight line ! If you wanted to duplicate the effects of blending in some particular space (ie., and RGB space, or some other linear light space), the only way to do this is to color convert your CMYK etc. to the blending space, blend, and then convert back again (assuming you needed to return to the original space). It is possible to do this type of thing in OpenGL using texture mapping lookups to do the color conversion interpolation, but this obviously involves a number of steps. Graeme Gill. ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
