Hi all, I am trying to calibrate my Nikon D90 using Argyll CMS and a target from Silverfast (http://www.silverfast.com/show/dc-targets/en.html). I have the problem that there is no CHT file for this target. The layout (number of rows and columns) is like the ColorChecker SG but I could not figure out whether I can modify the ColorCheckerSG.cht to work with this target. You can find a hires photo here: http://flickr.com/gp/joero/7dvNN4 Is there any documentation describing the creation of CHT files for starters? Thanks, Joerg