Hi, I have been using the Little CMS Profiling tools to create profiles for my scanners. To date, I have thought they have worked very well.
However, I have stumbled across something which doesn't seem right, and I'd like to get some feedback. The device I am profiling at the moment is the Nikon Coolscan IV ED film scanner. I am profiling the raw scans from Vuescan 7.6.18. These raw scans are not very neutral - they have a green colour cast. When I create a profile, the Profile Checker reports excellent results - a max dE of about 2. The problem is that when I import the image into Photoshop (V7.0, on Windows XP), the image takes on a yellow cast. I am tagging the image with the LCMS created profile when I open the image. If I then convert the image to my working space, which is sRGB for this testing, the cast remains. It doesn't matter what intent I use - there is always a colour cast - the greyscale is never neutral. (absolute intent results in a reddish cast, whereas relative intent results in a yellow cast). If I use the TIFFICC utility to convert the image from the same scanner profile to sRGB, the results look about the same as Photoshop, although I have not yet inspected pixel values closely. Now, there is a way to get what I consider to be excellent results (a totally neutral looking IT8 scan). All I have to do is convert to ANY profile that has a white point of D50, using absolute intent. Voila! Problem gone. After that, I can use relative or perceptual to go into any other space. The Profile Checker reports that the white point of the scanner profile is 5481K. I get the same result using TIFFICC - if I convert to a profile with a white point of D50, the result is excellent. Is this normal/expected behaviour? Greg. ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Lcms-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/lcms-user
