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Author Topic: Green/blue color cast with scanner profiles  (Read 1022 times)

BrianToth

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Green/blue color cast with scanner profiles
« on: April 04, 2018, 12:53:45 PM »

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!
« Last Edit: April 07, 2018, 10:26:09 PM by BrianToth »
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degrub

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Re: Green/blue color cast with scanner profiles
« Reply #1 on: April 04, 2018, 01:08:56 PM »

Since i did not see it mentioned - Is your monitor profiled ?

Does a print match what you see or are you going that far yet ?

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TonyW

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Re: Green/blue color cast with scanner profiles
« Reply #2 on: April 04, 2018, 02:12:06 PM »

...

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.
..
Brian, with respect, I really think that you are making the whole process more complex than it needs to be and would suggest that you may want to reconsider your approach.

While you may not think it you are actually trying to restore old images and in that restoration, if you actually improve then surely this must be a good thing?  Looking at a B&W image from the 40's is likely to not actually appear as it did back then - it may have faded discolored etc.  Similarly, with colour you will have the same issues, in fact, the issues with correction likely to be greater.

When you are dealing with old images it is my experience that you are aiming for maximum image information in the scan over the accuracy of colour as it relates to the original in its current state.  Why would you want to accurately record how an image looks today after 70 years has taken its toll and changed the appearance from the way it looked originally?  I believe it is better to get the best scan you can and make corrections as required to obtain the best/most pleasing image.

This may go against the grain for you and maybe others but I would suggest you ditch the colour checker, the IT8 targets and profiles they will really not help you in your quest to get best images from old B&W and Colour images.  They would be of use if you actually had to colour match with best quality originals, but in this case just get in the way.

I would suggest scanning your images (crop to the image area ignoring the borders) in the required quality and in the scan software adjusting the histogram to get close to final result without clipping then in your editing application apply whatever you need to produce a pleasing image.  I only looked at one image you linked to and had the briefest of plays to get what  I think is a reasonable photo.  Adjust the density with curves and channel mixer to remove colour, oh and a touch of dodge to the right figure to lighten a tad.  Hope you are ok with me posting this?  Your original scan on top my minor changes underneath



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Mark D Segal

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Re: Green/blue color cast with scanner profiles
« Reply #3 on: April 04, 2018, 03:35:43 PM »

The Epson V800 scanner I believe also came with an entry level version of SilverFast. If that version gives you access to the SilverFast generic Reflective profile for the V800 (would be in Settings - Color Management Profile - Input), try it and see what happens. If you can't load that profile with the bundled version, download a trial copy of the upgrade to SilverFast 8 Ai which definitely allows you to colour manage the scans quite well.
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Mark D Segal (formerly MarkDS)
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nirpat89

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Re: Green/blue color cast with scanner profiles
« Reply #4 on: April 04, 2018, 03:54:57 PM »

Interestingly, I had the exact same problem of greenish color bias when calibrated with it8/2 target from Faust as discussed in this thread:

http://forum.luminous-landscape.com/index.php?topic=117912.msg976704#msg976704

Never did figure out why.  Finally I gave up using calibration and eye-ball corrected the final scans. 

:Niranjan.
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BrianToth

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Re: Green/blue color cast with scanner profiles
« Reply #5 on: April 04, 2018, 05:21:12 PM »

The Epson V800 scanner I believe also came with an entry level version of SilverFast. …

Yes, the v800 did come bundled with SilverFast 8. (I currently have 8.8 installed.) To be honest, I haven't spent much time with it because I had purchased the i1Studio before I made a decision about which scanner to purchase. And when I ran into my initial color issues with the IT8 targets, X-Rite and B&H figured there must have been something wrong with the v800 because it was "supposed to make excellent scans right out of the box". The bundled SilverFast wouldn't support my v300 for comparison so I resorted to just using Epson Scan and VueScan for all future tests. I also later purchased a v600, which wouldn't work with the bundled SilverFast either of course. Also, my copy of SilverFast won't scan to 48bit mode unless I put it in 48bit HDR mode.

That said, I did just do a test. (I hope I did it correctly.)  In SilverFast I went to Preferences > CMS and chose 'SFprofR (Perfection v800)' as the Input profile. I did a scan with every other option set to the default (e.g. '0'), in 48-24bit mode, and I got a TIFF with an embedded 'SFprofR (Perfection v800)' profile.

(I just noticed though that if I go back to Preferences > CMS I see that it didn't retain the chosen Input profile, so it probably wants me to choose an Internal profile as well. I was hoping to be able to compare the pure scanner profiles without doing any sort of transform, but even with the Internal profile set the Lab values between to two are pretty much the same… hmm.)

Anyway, the scan still exhibits a green/blue shift in the photo and the ColorChecker, but not as much as the X-Rite or Argyll IT8-based profiles. I can't do my own SilverFast profile without upgrading.

I uploaded those two scans to here.

Something I haven't been quite clear on: is it normal to have to adjust white balance on a scanned image after assigning a profile? I would think 'no', but maybe I'm just missing something simple?
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Mark D Segal

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Re: Green/blue color cast with scanner profiles
« Reply #6 on: April 04, 2018, 06:01:40 PM »

Of the two scans, the one that is not sRGB looks more natural (less saturation) and more neutral. There seems to me to exist a slight magenta cast in the frame of the Faust target, but the ColorChecker and the B&W photo look not too bad. For a comparison, I just did for you a scan of my ColorChecker using the canned SilverFast reflective profile for the V800 (same as for the V850 I'm using) and other settings in the CMS as attached. If you are on Windows, "ColorSync should say ICM. The result is also attached. It should look pretty neutral. A TIFF I made of it could be more neutral and more consistently neutral in the grayscale patches, but this is an acceptable starting point amenable to marginal improvement with a bit of tweaking in a post scan editing application or SilverFast itself.
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Mark D Segal (formerly MarkDS)
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smthopr

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Re: Green/blue color cast with scanner profiles
« Reply #7 on: April 04, 2018, 08:22:25 PM »

Yes, the v800 did come bundled with SilverFast 8. (I currently have 8.8 installed.) To be honest, I haven't spent much time with it because I had purchased the i1Studio before I made a decision about which scanner to purchase. And when I ran into my initial color issues with the IT8 targets, X-Rite and B&H figured there must have been something wrong with the v800 because it was "supposed to make excellent scans right out of the box". The bundled SilverFast wouldn't support my v300 for comparison so I resorted to just using Epson Scan and VueScan for all future tests. I also later purchased a v600, which wouldn't work with the bundled SilverFast either of course. Also, my copy of SilverFast won't scan to 48bit mode unless I put it in 48bit HDR mode.

That said, I did just do a test. (I hope I did it correctly.)  In SilverFast I went to Preferences > CMS and chose 'SFprofR (Perfection v800)' as the Input profile. I did a scan with every other option set to the default (e.g. '0'), in 48-24bit mode, and I got a TIFF with an embedded 'SFprofR (Perfection v800)' profile.

(I just noticed though that if I go back to Preferences > CMS I see that it didn't retain the chosen Input profile, so it probably wants me to choose an Internal profile as well. I was hoping to be able to compare the pure scanner profiles without doing any sort of transform, but even with the Internal profile set the Lab values between to two are pretty much the same… hmm.)

Anyway, the scan still exhibits a green/blue shift in the photo and the ColorChecker, but not as much as the X-Rite or Argyll IT8-based profiles. I can't do my own SilverFast profile without upgrading.

I uploaded those two scans to here.

Something I haven't been quite clear on: is it normal to have to adjust white balance on a scanned image after assigning a profile? I would think 'no', but maybe I'm just missing something simple?

The second scan you made doesn't look too bad at all.  The color checker looks pretty good.  I think you are just seeing the color of the old photographic paper from the print, and perhaps some UV effect from optical brighteners in the printed photograph.

I think you're good to go!
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Bruce Alan Greene
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BrianToth

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BrianToth
« Reply #8 on: April 04, 2018, 11:13:41 PM »

Of the two scans, the one that is not sRGB looks more natural (less saturation) and more neutral.

Thanks for the sample. Interesting to see the advanced profile options in the higher up version of SilverFast. 



I have a question though… my understanding is that the greys of the ColorChecker should be close to neutral, with perfect neutral meaning that R=G=B or in Lab that a*=b*=0.  For example, the X-Rite reference file for the ColorChecker shows patch D4 to supposedly have Lab values around 50.76, -0.13, 0.14. Patch D4 in the scan shows an RGB of 83, 94, 96 and Lab of 38.53, -6.335, -3.343.

While the photo does look acceptable with any of the profiles on its own, with the IT8-based profiles (or the built-in profiles) assigned it's very green/blue compared to the original. That's hard to judge without having the original side-by-side, so I was trying to go by the target patches as a less subjective measurement.
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Mark D Segal

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Re: BrianToth
« Reply #9 on: April 05, 2018, 08:41:06 AM »

Thanks for the sample. Interesting to see the advanced profile options in the higher up version of SilverFast. 



I have a question though… my understanding is that the greys of the ColorChecker should be close to neutral, with perfect neutral meaning that R=G=B or in Lab that a*=b*=0.  For example, the X-Rite reference file for the ColorChecker shows patch D4 to supposedly have Lab values around 50.76, -0.13, 0.14. Patch D4 in the scan shows an RGB of 83, 94, 96 and Lab of 38.53, -6.335, -3.343.

While the photo does look acceptable with any of the profiles on its own, with the IT8-based profiles (or the built-in profiles) assigned it's very green/blue compared to the original. That's hard to judge without having the original side-by-side, so I was trying to go by the target patches as a less subjective measurement.

Hi Brian,

In principle you are correct that the gray patches should measure close to their file reference values. In the sample scan I made there are deviations, which is why I said "A TIFF I made of it could be more neutral and more consistently neutral in the grayscale patches, but this is an acceptable starting point....." above. There are four reasons for it: (1) My CC card is about 15 years old; while kept in dark storage some of its colours could have shifted a bit over the years. X-Rite recommends replacing it every few years. (2) I used a canned profile rather than a custom profile; it's possible my V850 doesn't behave exactly like the one LaserSoft Imaging used for creating their packaged profile. (3) The quality of the target influences the quality of the profile, so it could be that superior quality targets would produce custom profiles that show better neutrality characteristics; (4) Producing exact colour reproduction from a scan is generally hard to achieve; for example, I didn't let the lamp warm up (not supposed to be necessary with this model, but who knows), lamp temperature can shift overtime, scanner hardware less than perfect; etc. Part of this issue is to align ones expectations with technical reality. Notwithstanding all I mentioned here, the very "quick and dirty" result I produced with a canned profile, as I said, is a good starting point for refinement in post-scan workflow.

In what I quoted from you above, I simply don't understand the sentence I put in bold. Please explain.
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Mark D Segal (formerly MarkDS)
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Doug Gray

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Re: Green/blue color cast with scanner profiles
« Reply #10 on: April 05, 2018, 02:39:03 PM »

I have 3 full size CCs. An old GMB one from around 2004, an X-Rite one from 2009, and an X-Rite "Classic" from 2017.

All the neutral patches are within 1 dE of each other and the a*, b* are within < 1 from neutral except the white patch which is slightly warm. b* between 2 and 3.

The sort of shift seen here is not from CC changes. The neutrals are the most stable patches over time. It's been a while since I profiled a scanner but I never saw anything like these variations. Something is wrong in the process. These differences are way too large.
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Mark D Segal

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Re: Green/blue color cast with scanner profiles
« Reply #11 on: April 05, 2018, 05:34:23 PM »

Referring to Doug's reply on the scan values:

The reasons I listed above are just generic possibilities. The least likely culprit is the CC card, as you say. I just checked mine with my i1Pro2 and it's good - if it wandered at all, it's really minor. i.e. the L* values are within no more about 2 dE from where they are supposed to be, and the a* b* values are on the whole less than 1 dE from 0 save for two readings - the worst 2.76. 

Forget about the example I put up yesterday - it wasn't a designed accuracy test. I just wanted to get a quick impression of whether it would produce visibly noxious results scanning the way one would normally scan every day photos, so I adjusted the tails of the histogram, scanned it in ARGB(98) and then converted it from TIFF to JPEG. So it's been mangled from a  perspective aimed at proofing the accuracy of the scan workflow. It needed a different kind of scan set-up to assess accuracy of the profile and the scanner. But that's not all that's "wrong", because having produced a result with a group of settings that produce results as faithful to the values on the CC card as I could manage it with the V850, there are still issues with the deeper grays, but much less serious than yesterday's. In particular, apart from the changed CMS settings, no histogram adjustments in the "Unadjusted" exercise.

The attachments pretty much tell the story, so I won't go into muchdescription here. Anyone who needs clarification or further explanation, please ask and I'll do so. Re the panels of numbers, perhaps I should just explain up-front: the "ADJUSTED" set are yesterday's settings provided yesterday. The "UNADJUSTED" set underneath are today's settings, selected to produce the closest scan to the original card from scanner through SilverFast through opening in Photoshop, all attached to this post.

What I find most troublesome are the "differences of the differences" as between cols, HIJ involving eyedropper readings from the scan opened in Photoshop versus columns NOP involving readings with SilverFast's densitometer of the scan open in SilverFast, using nominally the same internal working space profile and Absolute Rendering Intent in both applications.

Sorry forgot to mention -  this is still the canned profile. I should repeat the scan with the same settings and my custom profile to see what improves.
« Last Edit: April 05, 2018, 05:39:48 PM by Mark D Segal »
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Mark D Segal (formerly MarkDS)
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BrianToth

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Re: Green/blue color cast with scanner profiles
« Reply #12 on: April 05, 2018, 06:42:42 PM »

I have 3 full size CCs. An old GMB one from around 2004, an X-Rite one from 2009, and an X-Rite "Classic" from 2017.

All the neutral patches are within 1 dE of each other and the a*, b* are within < 1 from neutral except the white patch which is slightly warm. b* between 2 and 3.

The sort of shift seen here is not from CC changes. The neutrals are the most stable patches over time. It's been a while since I profiled a scanner but I never saw anything like these variations. Something is wrong in the process. These differences are way too large.


Hi Doug,

Thanks for this info, that's very good to know.  Do you have any experience with the Digital ColorChecker SG?

When I make profiles using the ColorChecker 24, the patches of the scanned target do match the reference values, which is what I would expect. But when applied to the photos they end up a bit too warm. It was suggested to me by X-Rite, and I've read from others, that the 24 patches are probably not really enough for a great scanner profile. Wondering of the Digital ColorChecker SG would be a better solution given it's made with a similar manufacturing process to the CC24, but with whiter whites, blacker blacks, and many more patches.

The drastic color shift only seems to be a product of the IT8 profiling or when using the manufacturer scanner profiles. Obviously I'm curious why, but if the Digital ColorChecker SG bypasses the problem, that'd be easier. :)
« Last Edit: April 05, 2018, 08:28:57 PM by BrianToth »
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Doug Gray

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Re: Green/blue color cast with scanner profiles
« Reply #13 on: April 05, 2018, 07:18:59 PM »


Hi Doug,

Thanks for this info, that's very good to know.  Do you have any experience with the Digital ColorChecker SG?

When I make profiles using the ColorChecker 24, the patches of the scanned target do match the reference values, which is what I would expect. But when applied to the photos they end up a bit too warm. It was suggested to me by X-Rite, and I've read from others, that the 24 patches are probably not really enough for a great scanner profile. Wondering of the Digital ColorChecker SG would be a better solution given it's made with a similar manufacturing process than the CC24, but with whiter whites, blacker blacks, and many more patches.

The drastic color shift only seems to be a product of the IT8 profiling or when using the manufacturer scanner profiles. Obviously I'm curious why, but if the Digital ColorChecker SG bypasses the problem, that'd be easier. :)

The CC SG is good for making profiles as it has a surprising large number of patches that are rather saturated. They also are mostly the darker ones that you might not guess are that saturated. Many way outside of sRGB unlike the standard CC where only the cyan patch exceeds sRGB.

That said, using the CC SG requires much more care. Because it has a semigloss surface (hence offers more saturated colors), it is very susceptible to specular reflections from the environment.  My use of it in the past was to profile cameras for reproduction purposes (scene referred). To deal with the specular reflections I would use a large, black umbrella with a hole cut in it for the camera lens. This in addition to illuminating it evenly at 45 degrees. That setup most closely replicates the geometry that the patches are measured with a spectrophotometer.

I don't know whether the SG surface is an issue with scanners. However, it does have a larger gamut along with more colors. I haven't done any critical work in a long time with scanners.

I do find your problems with the IT8 odd. OTOH, my workflow with both camera and back in the day, scanner profiles, is somewhat different. I assign, then convert to Adobe RGB, the generated profiles in Photoshop to images processed the same way as the targets used to create the profiles. While somewhat unorthodox, I understand how and why that works. I have never tried the IT8 approach Vuescan incorporates though I have used Vuescan. For one thing I find their description opaque. I want to understand the math of what I do.
« Last Edit: April 05, 2018, 07:22:47 PM by Doug Gray »
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BrianToth

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Re: BrianToth
« Reply #14 on: April 05, 2018, 08:27:51 PM »

Quote
So, While the photo does look acceptable with any of the profiles on its own, with the IT8-based profiles (or the built-in profiles) assigned it's very green/blue compared to the original.


In what I quoted from you above, I simply don't understand the sentence I put in bold. Please explain.

Hi Mark,

Sure, I worded that horribly. :D

If I assign my IT8-generated profiles to the scans… they do look better than the "RAW" image that came out of the scanner. Same for scans made with either the Epson Scan-supplied profile, or the SilverFast Epson profile. So without anything to compare them too, I'd say they're good and look fine. But when compared to the original (especially when printed out and compared under the same lighting) they're noticeably color-shifted. This is hard to demonstrate though because obviously I don't have a way to accurately share what the original looks like, and I'm not very good at explaining colors anyway. So that's why I was trying to go by the target patches as a less subjective measurement. Numbers are easier for me to explain and understand. But I've also read that the numbers might not always tell the whole story with this stuff. :)

The exception to this is my profile made with the CC24. If I assign that profile, then the CC24 patches match the reference file almost spot-on, but other scanned items end up a bit too warm. This may simply be a limitation of only having 24 patches to work with though and perhaps a different target would solve my issue in that regard.

Hope that makes more sense.
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BrianToth

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Re: Green/blue color cast with scanner profiles
« Reply #15 on: April 05, 2018, 08:34:29 PM »

Forget about the example I put up yesterday - it wasn't a designed accuracy test.  …

No, thanks for taking the time to provide the examples! Both of your posts above have actually been very informative as I don't have access to v850 to test. And it looks like your results are actually very similar to what I'm seeing with my equipment and that is actually good news to me. I might have some more thoughts/questions about your results after I process all the info you shared.

Sorry forgot to mention -  this is still the canned profile. I should repeat the scan with the same settings and my custom profile to see what improves.

If you do happen to attempt it with your own custom profile, I'd be very curious to see the results. I'm assuming based on other posts I've come across of yours that you used an IT8 with the built-in SilverFast AI profiling? When I first started running into this problem I wondered if I would've had better results with the v850 kit vs my own profiling.
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Mark D Segal

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Re: Green/blue color cast with scanner profiles
« Reply #16 on: April 05, 2018, 09:16:21 PM »

Brian,

V800 and V850 - same principles of colour management apply, so if you are using a V800, everything I say about colour managing a V850 is applicable.

Let's focus mainly on three things:

(1) Making profiles
(2) Selection of where to profile the scanner
(3) Selection of colour working space ("internal" profile)

(1) Making profiles: The SilverFast Auto IT8 process is the easiest, most practical approach I've ever worked with, and the results are generally very usable. I've tested the X-Rite approach (see my article on the Epson V850 scanner, found it convoluted and cumbersome and no more accurate than SilverFast Auto IT8. To use it, however, you need the LaserSoft Imaging IT8 targets, because it involves a bar code on the target. There are not enough patches in a CC24 to make adequate scanner profiles. The CCSG was not designed for scanner profiling. It is best to use bespoke scanner profiling targets.

(2) Selection of where to profile the scanner: you have essentially two choices: (i) in the scanning process, or (ii) in Photoshop after the scan is made. For option (i) you select ColorSync/ICM in the upper section Color Management, Input to working space. Then in the middle section - Profiles - for input you select your scanner profile, whether a custom one or the supplied canned one. For option (ii), instead of ColorSync/ICM in the Color Management Section Input to Internal you select <none> because you will not be colour managing in SilverFast. If you select <none> here, then there will be no choice of a scanner profile for Input in the Profiles section; rather you will assign the scanner profile to the photo when you open it in Photoshop and then convert the image to the preferred colour working space (ARGB(98), ProPhoto etc.).

(3) Selection of Color Working Space (the "internal" profile): We generally recommend using a wide space because scanner colour spaces tend to be wide and if the scan will be sent to a modern inkjet printer, and especially using luster/gloss papers for printing, the gamut can be wider than aRGB(98). So ProPhoto is a good choice provided you make the scans in 16-bit to avoid banding that can happen if there are too few levels for the size of the colour space.

Not mentioned above, select the Rendering Intent that makes the image look best to you. This manages how out-of-gamut colours are handled.

For the monitor, you want it to be properly calibrated and profiled and ColorSync to be active in SilverFast CMS Color Management section, "Working Space to Monitor". SilverFast will then use your active monitor profile.
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Mark D Segal (formerly MarkDS)
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Stephen Ray

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Re: Green/blue color cast with scanner profiles
« Reply #17 on: April 05, 2018, 11:51:34 PM »

I have 3 full size CCs. An old GMB one from around 2004, an X-Rite one from 2009, and an X-Rite "Classic" from 2017.

Pffft, real men use color checkers from the '70s.

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nirpat89

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Re: Green/blue color cast with scanner profiles
« Reply #18 on: April 06, 2018, 09:52:08 AM »

Hi, Brian:

It is a little too much for me to keep abreast of this thread so I may be wrong to surmise this generally:  when you create a profile using Faust's it8 target, you get the luminosity values in the ball park but the a, b values show green/blue shift.  If this is true, and since that matches my experience exactly on a different scanner (Epson 3200,)  perhaps time to question the quality of Faust's targets.  Given that they are so cheap, may we get what we pay for. 

:Niranjan.
« Last Edit: April 06, 2018, 10:27:51 AM by nirpat89 »
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Mark D Segal

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Re: Green/blue color cast with scanner profiles
« Reply #19 on: April 06, 2018, 10:16:34 AM »

Hi, Brian:

It is a little too much for me to keep abreast of this thread so I may be wrong to surmise this generally:  when you create a profile using Faust's it8 target, you get the luminosity values in the ball park but the a, b values show green/blue shift.  If this is generally true, and since that matches my experience exactly on a different scanner (Epson 3200,)  perhaps time to question the quality of Faust's targets.  Given that they are so cheap, may we get what we pay for. 

:Niranjan.

I wouldn't jump to any conclusions on the quality of Faust targets. There are a number of variables at play here and unless you can isolate the particular influence of each you can't reliably pinpoint the culprit or culprits.
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Mark D Segal (formerly MarkDS)
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