Thanks all for the feedback. I noticed the option to create a test image with timage. This shows the problem I'm have quite good. I uploaded an example here: http://www.heck.dds.nl/timage.tif Open this in a program that does NOT apply color management such as windows Picture and Fax Viewer. On the top you see what Photoshop does when using the profile generated with argyll for a daylight temperature of 6500K (as this matches what the colorvision software does). The bottom one is the same image without any color management. The problem is in the blocky character of the argyll profile. The colorvision profile is much smoother like the bottom one. As is the original profile as provided by samsung for this monitor. (I expect the same problem is bothering me under Linux.) Anyone even seen this before and knows what causes this? Thanks, Luud