on 02.04.2012 08:54 Graeme Gill said the following: > Andreas F.X. Siegert wrote: >> I use "colprof -v -q m -a m -b n" >> >> Is there a way to influence the brightness? > Yes there is, but you need to understand what you are asking of > the system when you make a profile. The default ICC assumption > is that you want the white of your test chart to be perfect white > in the profile. > If your test chart is exposed so that it is not at full brightness, > then the profile will brighten everything up to make it so. Hmm, the chart (or actually the histogram) looks properly exposed when I take the test image. If only the white patch where blown I would understand it, but not only the white patch but also the next grey patch is completely (RGB) blown. If I look at the RGB values of the white patch in the app before I switch to linear to generate the test tiff, where should it be? How close to 100% or 255? > You can modify the white point scaling using the -U parameter. > Try a value > 1.0. Thanks, I'll try to fiddle with that. cheers afx -- http://afximages.com/