Hi Can anybody please tell me why using the Lab cLUT display profile cause lost dark shadow detail? The data set for profile generation is same and shaper+matrix profile (colprof -as) has no such effect in Photoshop CS2. Please note that it happens only in Photoshop. There is no difference using the Windows Picture and Fax viewer, which under Windows XP is not color corrected, right? If using the simple Windows viewer it does not matter if I set'n'load (dispwin -I) matrix or cLUT based profile. I'm using the fine B&W picture from http://www.northlight-images.co.uk/downloadable_2/bwtest_2.zip The loss in dark shadows is quite noticeable. It's best seen in the upper right crop with wooden beam where the wall turns mostly black, particularly below the beam. Of course it's noticeable on the other places also, on the radial gray gradient and the carved stone ceiling which loses lots of texture. The photo looks best using L* not gamma based tonal curve, but this is subjective. I don't know anything about L* except that it's pushed by some calibration software makers and that the radial gray gradient looks the best by using it. Best as in "visually linear" and "having the least sized black spot in the centre". But it doesn't matter, the effect of Lab cLUT vs. matrix profile is present also when using L* tonal curve. I did the profiles using the following flow: dispcal -v -yl -o -m -qh -g2.2 3008WFP-2.2 targen -v -d3 -g254 -f1200 -c3008WFP-2.2.icm 3008WFP-2.2 dispread -v -yl -k3008WFP-2.2.cal 3008WFP-2.2 colprof -v -qh -D"3008WFP-2.2-Lab" 3008WFP-2.2 colprof -v -qh -as -D"3008WFP-2.2-smatrix" 3008WFP-2.2 http://daemon.bsd.ee/~kalts/3008WFP-2.2-smatrix.icm http://daemon.bsd.ee/~kalts/3008WFP-2.2-Lab.icm http://daemon.bsd.ee/~kalts/3008WFP-2.2.cal http://daemon.bsd.ee/~kalts/3008WFP-2.2.ti3 thanks, -- Vallo Kallaste