Hi, I hoping someone here can offer some suggestions on a problem I’m struggling with.
I trying to help archive hundreds of old family photos and reproduce some of them to give out to family members. They range from the 1940s to 90s. I'm not trying to restore or improve upon any of the photos, I just want them to match as close as realistically possible to the originals given the tools at my disposal. I've been having some major problems with color casts when profiling my scanners, especially when using the IT8 targets, and I've been researching and testing for three months without making any headway.
My problem is the scanning. I've tried so many combinations of things now that I've lost track.
I have an i1Studio which came with a ColorChecker 24 Mini. I first tried using this to create a profile for my Epson v800 with the i1Studio software. The profile made a noticeable improvement over the generic out-of-the-box settings, but had the effect of slightly warming up the photos a bit too much. Enough that I called X-Rite to discuss the issue. They suggested I probably needed a target with more patches like an IT8 target.
The IT8 target resulted in a very green-blue cast and muddy looking… just awful.
Long story short X-Rite was of no help, Epson support was a joke, Wolf Faust tried to help, but maybe I did’t understand enough at the time, but now I have three IT8 targets and they all result in the same color cast. Recently X-rite has unhelpfully suggested that if I’m not happy with the profiles their software makes, I don’t have to use them. Argh. (The also made me rule out scanner problems before continuing to help, so now I also have a new v600 and an old v300… they all exhibit the same results.)
As an example, here’s what I’ve been doing to test lately:
1. Scan an IT8 target, ColorChecker 24, and a family photo at the same time to guarantee the same settings. (Usually this is with VueScan RAW output, but I’ve also tried Epson Scan with no color management, and VueScan with Color Balance set to None and Output Color set to Device RGB – just to see if a gamma corrected image would profile better.)
2. Make profiles from both targets.
3. Open the original scan that includes both targets and a photo in PhotoShop and assign a profile. RGB values stay the same, Lab values change, as expected.
What I see when I sample the Lab values in Photoshop seem to corroborate what I see with my eyes, even though I know this isn’t very scientific. The Delta-E values of the profile seem to suggest they should be very good. There’s an interaction between the scans of the two targets that also seem to demonstrate the problem:
If I apply the X-rite profile from the CC24, the Lab values of the patches on the CC24 scan are pretty close to the reference values. The photo looks pretty good, though maybe a bit more yellow and pink than the original – not bad on screen, but noticeable when sitting side-by-side with the original. The grey scale in the scan of the IT8 shows a red/yellow shift rather than being closer to neutral as described in the IT8 reference file.
If I apply the X-rite profile from the IT8, the whole image gets too bright and everything shifts to the green/blue. The CC24 scan demonstrates this well: what are supposed to be neutral grey have a large color shift.
Working under the assumption that I was dealing with some sort of whitepoint/color balance issue, I researched everything I could find about ICC profiles and related issues. X-Rite’s software is a bit of a black box… I don’t know what it’s doing. So I learned how to use Argyll and wrote a script to output every combination of profile type with and without the -u and -ua flags to attempt to force an absolute rendering intent. Argyll gave some good results, but still not “correct”, and I feel like I’m just flailing around without much direction at this point. I also sidetracked into DNG profiles to try to treat the scanner as a camera… interesting experiment, but not what I need right now. I’ve also noticed that with some of the Argyll profiles that if I later convert to a standard color space using Absolute Colormetric, that the brightness shifts back to a more realistic amount. X-rite told me I should’t need to do any converting after assigning the profile, so I just don’t know…
I’m also starting to wonder if just upgrading to a target like the
Digital ColorChecker SG would help me out. I feel like the CC24 does a good job, but just doesn’t have quite enough patches and the software isn’t quite extrapolating things as well as it could if it had more samples to work with. I just hesitate to throw more money at X-rite after they blew me off, but if it solves my issue I’m all for it.
Any suggestions would be appreciated. Happy to go into more details if requested, but this post was already way too long even after I skipped over a lot of things I’ve tried and researched.
I’ve uploaded my most recent test files here for anyone that want to check them out:
http://server.briantoth.com/luminous/Thanks so much!