I understand. If that was not true, it is an interesting coincidence to see the same outcome in two different independent cases. We both could have been doing same thing (or different) erroneous in the process, I guess. May be something amiss in the way VueScan does the number-crunching. We can learn where the problem lies, the process or the target by having one of us send someone else the target and have them do calibration with the a known good process and see what results.
:Niranjan.
Interesting that you had some of your own issues. I probably came across your discussion during all my research.
For what it's worth, the reason I ended up with three IT8 targets is that I initially suspected a problem with the first one. That first one was $60 from LaserSoft (i.e. SilverFast). I then bought two more from Wolf Faust ($10 ea). One on Kodak, the other on Fuji.
All three exhibit the same problem. For all I know, Wolf Faust manufactures the LaserSoft ones.
Either way, they all seem to perform the same, and according to my profiling results, the Delta-E values should be well within acceptable margins of error… which I would take to imply that there's no noticeable discrepancies between the target itself and its reference file.
I've also tried the following scan methods (for both generating the profile and future scans that are to use the profile):
- Epson Scan with "no color management" (turns off all settings). Output is still gamma(?) corrected or internally assigned some standard profile, but no profile is saved with the image.
- VueScan "RAW". Gamma 1.0, no corrections. (X-Rite doesn't like to make profiles from these, so mostly tried them with Argyll CMS.)
- VueScan with "Color: None", default values, output to Device RGB.
- SilverFast "RAW"
All methods produced pretty much the same results once the profiles were assigned to the image. Some had slightly better shadow details, etc. but without getting too fussy, they all had the same color shifts.
Also tried with a v800, v600, v300. The v300 has very noisy blacks, but otherwise they all look very similar.
Using Argyll CMS from the command line gave me a ton more control but the cLut profiles give the same color shifts. Some like the Shaper Curve profiles look pretty good on the screen, but that's a whole other can of worms… too many options and I don't know which I'm supposed to be focusing on. I also don't know what type X-Rite produces to compare with. Maybe there's a way to figure it out using the ColorSync utility?
I attached a PDF of a small sampling of the Lab values comparing the four profile results.