More on Adobe ACE gamut mapping

In my last post, I tried to suss out what Adobe is doing with their Relative Colorimetric gamut mapping, and found that it was essentially clipping in destination space. Reverse engineering Adobe’s gamut mapping In this post, I’m going to look at some of the details of what it’s doing. Let’s start out by looking at chromaticity diagrams at several luminance levels. Here’s what happens at L* = 50. The purple dots are points in ProPhoto RGB (PPRGB), and the arrows indicate the mapping to sRGB. If the arrows all pointed towards the D65 white point, that would mean that there are no hue shifts in CIELuv. Sadly, that is not the case. We can learn more by looking at high and low luminance. The low luminance samples are all in the cyan to blue region. Here’s a plot at high luminance. Mostly yellows. The post More on Adobe ACE gamut mapping first appeared on the last word.