Luminous Landscape Forum
Raw & Post Processing, Printing => Colour Management => Topic started by: James Haswell on May 28, 2016, 11:08:26 am
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Hi there.
I've been scanning and printing for a little over five years now and I have an issue that just won't die. Each time I think it has been solved, it hasn't.
My problem: Take an old piece of paper / art / map. The paper typically has a yellow / orange tinge to it. Scan this into a Adobe RGB color space. Save as a TIF. Open in Photoshop - print to printer. The print has a magenta / pink tinge instead. The print looks the same if I use the correcr paper ICC or if I let the printer do the color management in Adobe RGB space.
Thinking of the time, paper, and Ink I've wasted trying to color match brings a wave of crushing depression.
I'm not trying to match to the screen, mind you, just the original. I know things like contrast and sharpness will need to be modified, but I would think with near 15k worth of equipment, I should be able to get an ok looking color match mostly out of the box, since I've done no manipulation. The issue has existed over many PCs, and the 9900 has been replaced with a newer 9900 (another story) so I doubt that it's drivers or a printer hard ware issue. I've also had the issue with other scanner, so I don't think it's a scanner hardware issue.
I don't really have any budget for expensive color profiling software, but I don't really see why I would need it, I have the impression that I'm trying to do something very simple.
I have read many posts. I've uninstalled drivers, I've tried just about every ICC profile.
The closest I can get with this example I'm going to show is to print with no ICC and the printer color settings off. So -no color management at all. This give a dull, very low saturation print, but at least it doesn't have a pinkish cast.
Can anyone save me from this madness?
Thanks ahead of time,
James
My equipment:
Photoshop CC
Epson 9900
Contex HD iFLEX
(http://www.stompinggroundsprints.com/cast.jpg)
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You don't mention what scanner software you are using and whether you have profiled the scanner. Perhaps you know, but just to remind: it too must be colour-managed.
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The print has a magenta / pink tinge instead
First thing to do is decide where this color cast is being produced. The scan or the print or a bit of both? I'd output a color reference image that has no such cast:
http://www.digitaldog.net/files/2014PrinterTestFileFlat.tif.zip
This is in Adobe RGB (1998). How's it look when you print it using the identical settings used for the scan?
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Regarding scanner software: I'm using contex's NextImage, which, I believe, is the only software that the iFLEX supports.
The Image is in the Adobe RGB color space and the ICC profile is that of the scanner device (as recommended by Contex)
So Here's an image of a good print. What I don't like is that I had to modify the levels and brightness in an arbitrary way.
I want a reliable process. I would think it would be the same for every image.
I'm attaching a link to a slice of the image file as well.
(http://www.stompinggroundsprints.com/nocast.jpg)
casts.tif (http://www.stompinggroundsprints.com/casts.tif) <-- Looks like this'll take about an hour to upload to my server. You might want to wait to grab it.
Thanks
James
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Are you setting a white point ?
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Are you setting a white point ?
Where would I be doing that?
The magenta casts comes with NO modifications once I open the scanned file in photoshop. So if you're asking about white balancing or color correction in PS, I'm not doing that.
Thanks
James
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Andrew's recommended diagnostic to see whether the problem originates from the scan or the printer makes sense. I think you should start the corrective process by doing that. If the print of the target emerges without the cast you see from the scan, then the problem will most likely be what I suggested it may be: you need to calibrate and colour manage the scanner. You still haven't indicated whether the scanner software you are using allows you to calibrate the scanner and select a good profile for the film you are scanning. And I should add, that scanning, no matter how good the software and the profiling, will not give you results that never need to be tweaked in a post-scan workflow. Scanner software such as SilverFast and Vuescan allow you to edit the scan before scanning it (SilverFast with more sophisiticated controls than Vuescan for this purpose), but I don't know what your scanning software allows. Whatever the scanning software, you can always elect not to edit the scan before scanning it and saving the edit work for Lightroom or Photoshop post-scan. If you do this, you need to make sure that you produce a colour-managed scan, reasonably "open" tonality without clipped highlights or shadows, as those will be unrecoverable if you scan them out.
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Alright.
So I printed the test image, scanned it, then printed the resulting unmodified file.
The scanning software has settings for color space, under which I've chosen Adobe RGB, and ICC, under which I've chosen the Device's ICC at the recommendation of Contex, the scanner manufacturer.
It also has several other post scan processes.
SilverFast does not support contex scanner, as far as I can tell from their site.
Here's a couple images comparing the pre and post scan images. Original is on the left.
I'm hoping that something I can do in the scanner post scan processing will be able to get me to a place where I would be able to have a relatively close color match without any fiddling in photoshop.
In case it's not clear, I really appreciate everyone's input on this and your patience with me.
Thanks
James
(http://www.stompinggroundsprints.com/prepost1.jpg)
(http://www.stompinggroundsprints.com/prepost2.jpg)
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The scanner does have a self calibration with a provided input sheet.
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Let's take one thing at a time. What printer are you using, what paper are you using, what profile for the printer/paper combination are you using, what Rendering Intent and Black Point Compensation (on/off), are you printing from Photoshop with Photoshop manages colour and is your printing workflow colour-managed taking all these factors into account? When you made the print of Andrew's target, before we get to any scanning, did the print pretty well match the image of the target on your monitor?
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James,
It appears your normal work is reproduction of civil engineering documents based on the test scan and the following equipment:
Photoshop CC
Epson 9900
Contex HD iFLEX
You are right that the monitor and it's profile are irrelevant. Andrew's point about breaking down the problem to smaller steps is a good one.
Repro workflow is simple. Much more than photographic work which requires artistic judgement calls.
Basically, your scanned image color values should be as close to possible to the original document and not white point adjusted. Most repro scanners can be set to do this or do it automatically. In photography, this is called "Scene Referenced" and is default mode for most scanners. The L*a*b* values of your test strip background are around L*=87, a*=3, b*=16 but vary a bit as the aged paper varies. Very typical of older engineering drawings.
When you print images from a scanner for repro purposes you should set the printer rendering intent to Absolute Colorimetric. Doing these two steps obviates the need to use the monitor for anything at all color related.
The cheapest approach to test each of these is to scan an X-Rite Colorchecker, then print it as described above. They should match within reason. You can also check the scanned L*a*b* values in Photoshop to see if there is any significant error in the scan process.
If this doesn't resolve it I would get a used I1 Pro spectrophotometer. You don't need any software other than to download ProfileMaker 5 from X-rite. Without a license you can still use the Measure Tool to read printed spot colors so you can evaluate exactly how well the scanner is reproducing the paper background and how well the printer is reproducing that color which is how Absolute Colorimetric intent works.
Something like this:
http://www.ebay.com/itm/EFI-ES-2000-X-Rite-i1Pro-Rev-E-Spectrophotometer-/291774297594?hash=item43ef1a75fa:g:-akAAOSwoJZXR0dz
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When you scan Andrews test print that shows the "dog in snow" as normal (neutral) looking, does the preview on your monitor both in the scanner software and finally viewed in Photoshop show the pinkish blue cast?
If it does, then you're going to have to bypass the scanner's implementation of ICC color management that affects monitor previews or you have to edit by eye within the scanner software, save the settings and apply to the rest of the scans. Or rummage through the list of other ICC canned profiles in the scanner software that gets it the closest if those options exist that gets rid of this cast.
I had an Agfa Arcus II flatbed scanner over 15 years ago that allowed me to choose a canned (supplied by Agfa) ICC scanner profile that did a better job than building one from an IT8 target which tended to over saturate scans and boost the red channel in warm colors once I clicked on a neutral target.
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When you scan Andrews test print that shows the "dog in snow" as normal (neutral) looking, does the preview on your monitor both in the scanner software and finally viewed in Photoshop show the pinkish blue cast?
That file isn't to be scanned, only printed.
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That file isn't to be scanned, only printed.
Yeah, but that's what he's showing in the posted image of the prints captured with a Samsung digital camera...
So I printed the test image, scanned it, then printed the resulting unmodified file.
It's indicating that your test image prints as it should which means his monitor and printer render and match color as intended.
The scan of that print shows a huge color table mismatch or the inks in the dog in snow have some type of optical brightener the scanner is picking up.
The OP is not being clear about monitor to print matching using a known test image such as yours.
We need to know if the scanner software preview is showing an accurate scan and that scan preview is the same in Photoshop.
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As I mentioned above, I think the OP needs to work this through methodically from one stage to the next. First make the print of Andrew's test image (he's done that now) and see whether the print pretty well matches his monitor. If it does, his colour cast problem is coming from the scan stage, and most likely either a scanner calibration/profiling problem or a scanner defect. I do not know the scanner or its software, so I cannot advise; but at the least it is important to nail where the source of the problem is so that it can be fixed.
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As I mentioned above, I think the OP needs to work this through methodically from one stage to the next. First make the print of Andrew's test image (he's done that now) and see whether the print pretty well matches his monitor. If it does, his colour cast problem is coming from the scan stage, and most likely either a scanner calibration/profiling problem or a scanner defect. I do not know the scanner or its software, so I cannot advise; but at the least it is important to nail where the source of the problem is so that it can be fixed.
He's got good equipment. The scanner comes with IT8 charts for calibration/profiling. They even publish color specs for each of the vintage IT8 charts they provide the scanner with. The problem is either on the scanner side or printer side. James is not using the monitor for matching colors but going straight to print which is the proper path for reproduction work.
So, yes, he needs to break it down and find out which side (printer or scanner) has a flawed process. I'm guessing the scanner which is why I suggest scanning a Colorchecker and seeing what the resulting Lab values are in Photoshop. If that's a good match then print it out using Absolute and compare the print to the Colorchecker. Simplest approach if one doesn't have a spectro.
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Can you save a fragment of scanned image as jpeg and upload it here?
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He's got good equipment. The scanner comes with IT8 charts for calibration/profiling. They even publish color specs for each of the vintage IT8 charts they provide the scanner with. The problem is either on the scanner side or printer side. James is not using the monitor for matching colors but going straight to print which is the proper path for reproduction work.
So, yes, he needs to break it down and find out which side (printer or scanner) has a flawed process. I'm guessing the scanner which is why I suggest scanning a Colorchecker and seeing what the resulting Lab values are in Photoshop. If that's a good match then print it out using Absolute and compare the print to the Colorchecker. Simplest approach if one doesn't have a spectro.
Well, not clear whether he's focusing solely on repro or more generally on scanning a range of media hoping to get colour-managed results. Best he gets the whole workflow properly calibrated and profiled. I agree that scanning the ColorChecker is the correct next step, and I was going to also recommend this once I heard back on his view of whether the print of Andrew's chart comes out of the printer without a cast. We still aren't clear on that.
While his scanning equipment and software may be well-designed, there are of course all the questions about whether it is being used correctly for a color-managed workflow from scan to print. If the scanner profile is not adequately matched to the media being scanned such results are quite possible, and I suspected from the beginning this is likely where the problem may be. But we only get to know this one step at a time.
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Well, not clear whether he's focusing solely on repro or more generally on scanning a range of media hoping to get colour-managed results. Best he gets the whole workflow properly calibrated and profiled. I agree that scanning the ColorChecker is the correct next step, and I was going to also recommend this once I heard back on his view of whether the print of Andrew's chart comes out of the printer without a cast. We still aren't clear on that.
This brings up the issue of having a "reference image." Something that Andrew, amongst others, often raises to check color management. It is a real need amongst photographers. The reason I harp on using a Colorchecker for that purpose is that it's really the only widely available physically existing thing that also has a digital "reference image" available. It doesn't have to be. And it's not fully adequate. There can be many things a good image or set of images can provide. Someone should provide matte and glossy prints together with matching reference digital images printable in RC to retain colorimetric accuracy, for people to check their color management. While gamuts vary, most of the variation is between matte and glossy. One could easily produce limited gamut images that fit 99% of glossy and matte printers in RC and physical prints of these to help photographers check out their color management.
While his scanning equipment and software may be well-designed, there are of course all the questions about whether it is being used correctly for a color-managed workflow from scan to print. If the scanner profile is not adequately matched to the media being scanned such results are quite possible, and I suspected from the beginning this is likely where the problem may be. But we only get to know this one step at a time.
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This brings up the issue of having a "reference image." Something that Andrew, amongst others, often raises to check color management. It is a real need amongst photographers. The reason I harp on using a Colorchecker for that purpose is that it's really the only widely available physically existing thing that also has a digital "reference image" available.
That's why there's a color checker in that reference image.
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That's why there's a color checker in that reference image.
It's definitely a good thing you provide that in one of your principal images Andrew. But for best comparison one really needs to print a ColorChecker image at the same size and in Absolute Colorimetric then trim the white edges to avoid perceptual white adaption. Makes a really good profile check.
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It's definitely a good thing you provide that in one of your principal images Andrew. But for best comparison one really needs to print a ColorChecker image at the same size and in Absolute Colorimetric then trim the white edges to avoid perceptual white adaption. Makes a really good profile check.
Yes - both print it and measure it - then you really have a quantitative grip on differences between reference values and printed values.
But you are also correct in your previous post that the GMCC could be complemented by other reference images; there is such a set - the Roman 16 bvdm Reference Images from Germany. Not cheap, but everything you asked for.
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Yes - both print it and measure it - then you really have a quantitative grip on differences between reference values and printed values.
But you are also correct in your previous post that the GMCC could be complemented by other reference images; there is such a set - the Roman 16 bvdm Reference Images from Germany. Not cheap, but everything you asked for.
True, those are excellent reference images. Especially for checking out smoothness near gamut edges. Pricey though. But for a collection of images that exercises gamut boundaries they are hard to beat. Would be nice if someone provided both a few physical prints of images like Andrew has together with an in gamut,RC digital file to reproduce them on a color managed system. Business opportunity Andrew?
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It's definitely a good thing you provide that in one of your principal images Andrew. But for best comparison one really needs to print a ColorChecker image at the same size and in Absolute Colorimetric then trim the white edges to avoid perceptual white adaption. Makes a really good profile check.
You can be off by as much as 5 Lab numbers and not see much of a visual difference. Andrew's YouTube video on Delta E bares that out. I think Andrew's reference image for the OP's situation is a good enough indicator that something is messed up with his scanner as the scan and subsequent print of the correct looking print of the reference image shows a Delta E that's way over 5 evident in the overly blue white dog in snow image. My $50 Epson "All In One" does a better job of accurate duplication of documents than that.
Even the ColorChecker colors in Andrew's reference image of the print of the scan are hardly affected visually but more pronounced in the gray patches.
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You can be off by as much as 5 Lab numbers and not see much of a visual difference. Andrew's YouTube video on Delta E bares that out. I think Andrew's reference image for the OP's situation is a good enough indicator that something is messed up with his scanner as the scan and subsequent print of the correct looking print of the reference image shows a Delta E that's way over 5 evident in the overly blue white dog in snow image. My $50 Epson "All In One" does a better job of accurate duplication of documents than that.
Even the ColorChecker colors in Andrew's reference image of the print of the scan are hardly affected visually but more pronounced in the gray patches.
Agreed. Neutral tone deviations are more easily visually sensed than the more saturated CC colors. dE2k is the better metric for color difference to account for that.
No doubt something is wrong with the OP's process. He's probably looking at dE's of 10 or more.
It is hard to see differences of 5dE. Particularly, if the two prints are not adjacent or the differences are not in neutral tones. Also, many or most of the CC colors are in areas where the dE2k is much lower than the dE76 and dE2k is closer to a perceptual metric than dE76. The OP's work as described is much less sensitive to color shifts than most all photographers. He's got a problem with blue/yellow shifts that seems quite strong. It's interesting that it keeps popping up for him over many years and different printers.
One wonders where the problem is. It's not even close to normal color behavior.
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It's interesting that it keeps popping up for him over many years and different printers.
That would point heavily to a problem with scanner colour management or performance. From what I read about it, their NextImage scanner software does support ICC colour management, so that being the case the question then turns to how the OP is using it, or whether the scanner is somehow defective.
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That would point heavily to a problem with scanner colour management or performance. From what I read about it, their NextImage scanner software does support ICC colour management, so that being the case the question then turns to how the OP is using it, or whether the scanner is somehow defective.
I'm leaning that way too and for the same reasons. I'm a believed in measuring. He should scan a colorchecker and compare lab values to the published.
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I'm leaning that way too and for the same reasons. I'm a believed in measuring. He should scan a colorchecker and compare lab values to the published.
Yes, and as necessary, adjust his colour management settings in the scanner software until he finds the combination of settings whereby the measurements of the scanned output more or less cohere with their reference values.
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My problem: Take an old piece of paper / art / map. The paper typically has a yellow / orange tinge to it. Scan this into a Adobe RGB color space. Save as a TIF. Open in Photoshop - print to printer. The print has a magenta / pink tinge instead. The print looks the same if I use the correcr paper ICC or if I let the printer do the color management in Adobe RGB space.
I think you need to re-adjust your expectations with regard to what "out of the box" color can do for you.
Pre-canned profiles will typically be accurate to somewhere in the range of 2-10 delta E. Custom made profiles somewhere in the range 1-5 delta E. Typical workflows are all relative colorimetric based intents, where it is assumed that white is the white of the media (and it's wired up to make it that way), so the color inaccuracy manifests itself in areas other than white, and the above color accuracy is quite workable.
When using a proofing type workflow where you are trying to emulate one media color with another (Absolute Colorimetric intent), things get a whole lot more critical. I've seen many cases where 1 delta E is not enough - the media color error needs to be < 0.5 delta E to be a visual match. So "by the numbers" custom profiles may not quite enough, since the accuracy and repeatability of graphic arts instruments like the i1pro may not quite be good enough.
And then there are the other complications, such as the destination media simply being out of gamut of the source, FWA/OBE's in the paper resulting in color shifts because the instrument isn't "illuminating" the paper the same way you are viewing it. And then there is the scanner, which typically is not colorimetric (i.e. it doesn't see color the same way humans do), so profiling it with a test chart will not be accurate to better than 3-10 delta E, unless the test chart has exactly the same media and colorants as what you are scanning, and the CIE reference values are made with the same illuminant as you will evaluate the result in. One of the errors you may well see with a profiling chart being different media to what you are scanning, is a white point error - by default (i.e. Relative Colorimetric) a perfectly profiled scan should result in the media color being removed. Typically people work around any such error by manually adjusting the white point of a scan to make the media perfect white.
[ And I won't complicate this explanation any more by going into observer variability. ]
Now all this doesn't mean that you can't solve your problem, or that it's not just one of these things that is causing the majority of the color shift (hopefully some of the preceding suggestions from people will help), but saying that "you spent a lot of money" so that it should "just work" isn't realistic, when you are using a less common workflow. A serious, high accuracy color instrument could set you back in the vicinity of $20,000 and up, so what constitutes "a lot of money" is relative.
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And then there is the scanner, which typically is not colorimetric (i.e. it doesn't see color the same way humans do), so profiling it with a test chart will not be accurate to better than 3-10 delta E, unless the test chart has exactly the same media and colorants as what you are scanning, and the CIE reference values are made with the same illuminant as you will evaluate the result in. One of the errors you may well see with a profiling chart being different media to what you are scanning, is a white point error - by default (i.e. Relative Colorimetric) a perfectly profiled scan should result in the media color being removed. Typically people work around any such error by manually adjusting the white point of a scan to make the media perfect white.
For example I made a custom scanner profile using an Agfa silver halide photographic paper it8 target that worked pretty well scanning my family photos printed from silver halide minilabs. But when I scanned old, slightly yellowish white fabric containing dye print patterns of forest green, blue, rose red and deep purple, the yellowish white looked pretty accurate but the deep purple almost looked black, forest green almost electric grass green, blue was spot on and deep rose red was an intense fuchsia.
In retrospect I wonder if I should've just reduced global saturation instead of editing global WB & Hue/Sat of individual colors within the scanner software. I've overlooked that simple approach many times to my frustration when attempting to get accurate color shooting Raw with my DSLR. Saturation appearance can really mess up color judgement in finding where the problem lies.
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Taking the (adjusted to look correct) photo of the side by side print and original, then correcting the white point to produce the same yellowed background the big difference is the highlighted "Village of Clyde" center square.
The document itself is just a faded and slightly yellowed/tanned black & white civil engineering drawing. The more intense "yellow" portion was probably made on the original with a yellow highlighter. These are highly fluorescent but will fade somewhat over time. So the differences could well be from uV. The actual scanned image does not have as significant yellow hue shift and it's darker as well. However, the yellowed background, unlike the highlighted square, is very close to the supplied pictures of the print and original.
My guess is that the scanner has very little uV compared to his room lighting or the luminance and yellow (high b*) would not be as intense as it is. It's also possible that the room lighting where the original and print were photographed might be an industrial very low CRI CLF. Check out the image he downloaded against the pictures.
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Have a look here: http://forum.luminous-landscape.com/index.php?topic=111295.0
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Have a look here: http://forum.luminous-landscape.com/index.php?topic=111295.0
It appears the problem reported here was occurring before May 28th (original post date), while the problematic Photoshop CC release occurred on June 20th. So unfortunately, Adobe's CM bug can't be blamed for this thread issue.