Soft-proofing and out-of-gamut colors

I am experiencing some oddities when soft-proofing a test picture for a commercial printing service. Maybe someone can help.

The situation is the following: the company provides you with a color profile for their printing machine, a digital test file (no color profile, but saved as sRGB for the mass market I believe) and they'll send you the printed photo to compare colors on your screen. The file consists largely of out-of gamut colors and not too surprisingly looks different from the print (especially the greens) when first opened in photoshop.

I am using a NEC MultiSync LCD2690WUXi2 wide gamut screen, software calibrated.

I have then used the photoshop softproofing option with the given profile and found that all colors that were inside gamut are a perfect match (in particular the greytones are very accurate when comparing softproof and real print), but this is not the case for out-of gamut colors.
For example much of the saturated green colors are way more towards dirty yellow on my screen compared to the printed image (the greens look more towards cyan there). I have deinstalled the software color calibration and while the colors are slightly different, the general issue is the same - out of gamut colors are way off. So I guess it has nothing to do with my color calibration but rather with the way photoshop shows out-of-gamut colors in various profiles.
Oddly, I get a generally better result if I convert the picture first to CMYK and then softproof, now the saturated greens look quite close to the print, but it is not a perfect workaround, as the saturated blues don't match as well as the initial softproof without conversion to CMYK.

I have done the same testing on a Lenovo Thinkpad which is also software calibrated (but has obviously a much smaller color range). Now the odd thing is that soft-proofing on the Thinkpad gives quite a good preview of the real printed image. So I guess it must have something to do with the wide gamut screen, but I'm clueless as to what I could possibly do different, I've played with all the softproofing options with no success.

I'm not sure wether it is a good idea to publicly provide names and links of the company I used in here, but if somebody wants to try and do the same testings as me, please send me a message and I will provide links in private (though I think they'll send you the test picture only in Germany, Austria and Switzerland).

Any suggestions on the subject are most welcome.

Ingo

Ingo,

Make sure that you are looking at different rendering intents in your soft proofing process as they will affect the way out of gamut colors look. Preceptual is my intent of choice typically but it will vary by image and device. Is this a photo printer or a commercial printer printing with an offset press in CMYK color space? CMYK typically has a problem with cyans, blues and purples and sRGB photo printers tend to go green in the bright yellow areas. This is makes accurate softproofing a pain but very imperative. If we can get more info we can give more details.

a) It's a photo printer.
b) I see very little difference between perceptual and relative colorimetric. Perceptual is closer to the real thing, but not by much.
c) The printed test picture is indeed slightly greenish in the yellows. The softproof has all inside-gamut colors alright, also the grey is really a very good match (it's a slightly cold grey). But all greens look way too warm in the softproof. The thing I don't get is why the softproof looks good on my labtop screen. This happens only for out-of-gamut colors and particularly the greens. I have found a few ways to simulate the green of the print, none of them seems very reasonable to me. Besides switching to CMYK and back (which kinda kills the blues) I can also desaturate the image a lot until the colors are in gamut (-55 saturation), then use a lot of vibrance to get saturation back. If I softproof after this manipulation, the greens look more like the real match, though not perfect.
d) Actually if I desaturate until the colors are in gamut, the softproof colors looks quite good to me, but once I up the saturation it seems to me that the greens become yellow (I guess the green channel clips first?).

I went back and read your post along with the second one and I have some thoughts...first, I would maybe not worry so much about matching the provided print if they have provided you with a color profile because changing the file to match the print is going to require burning and dodging and selective color maintenance. This is going to vary image to image. I would instead pull up one of the images you hope to print and see how many (if any) colors you have out of gamut. As you say, the colors in gamut match very well. There may be no reason to worry if the images you want to print are not out of the devices gamut...stress for no reason.

Secondly, use softproof to make your print look the way you want it to, watching out of gamut colors and adjusting those to bring them into gamut if necessary. Something to keep in mind (and this is the simplistic version) but perceptual rendering intent keeps the relationships between colors the same and when it draws out of gamut colors in it may shift colors that are in gamut in order to keep their relationships the same. Relative Colormetric typically only changes and brings into gamut those that are out and has less of an effect on existing in gamut colors. At times there is little to no difference between them visually and other times they are drastically different. It always helps to change intents to see the difference. That being said, if they built the intent in preceptual that is the intent I would recommend using. And vice versa with relative. Are they asking you to convert your file to their profile before sending it or will / are you supposed to leave it in a color space such as sRGB or Adobe RGB? I think you may be going through more stress than necessary trying to match a print that you won't be printing. Use it as a guide for in gamut colors and what way the out of gamut colors shift and do what you can on your images to bring all of your colors into gamut. I hope that helps and please post more questions if you have them. Good luck!

Les, thanks for your input. You're right that I do probably worry too much for the actual printing - when going through my photos, I seem to never have large areas out of gamut.

Still, it worries me a little that the softproofing doesn't work correctly - makes me fear that something is wrong mith my screen settings or my photoshop settings, but I can't figure out what it could be.

As for your final questions - they do specify that you should use relative colorimetric, and you're supposed to upload an sRGB file

Ingo, the reason the printing service is doing this is probably to reduce the frequency of disgruntled customers. By sending you a test digital file that you can softproof and compare to their test print, it gives you some level of confidence (or not) that the image you send them for printing will be satisfactory when it comes back.

If your own images rarely contain colors that would be out of gamut for this specific printing service's printer, or other similar color management challenges, then you may be safe enough to skip this exercise. But if you want to get more confidence in how your prints will come back, which is the purpose of this exercise and color management in general, then you may want to press ahead and understand / debug what is going on.

Reading the thread so far, I do suspect a color management faux pas. If I've followed correctly, you say there are many out of gamut colors contained in the test image, which supposedly is in the sRGB color space (even though it's not tagged). I don't know what photo printer is involved, but it would seem unusual for an sRGB test image to be wildly beyond the gamut that a good photo printer could reproduce. Can you say what specific printer it is? Further, you say that the out of gamut colors look off when viewed on your NEC wide gamut monitor (which has nearly the full Adobe RGB color gamut), but not when viewed on your ThinkPad which presumably has a quite narrow gamut display (probably substantially less than sRGB).

The combination of these two observations almost certainly means something is going wrong in the color management on your main workstation with the NEC monitor. It's a particular hallmark of color management missteps when narrow gamut images look wrong when viewed on a wide gamut display.

To diagnose the situation we'd need to get into specific details. If you want to pursue it, my first 2 questions are:

1. Can you post a screenshot of your Photoshop Edit > Color Settings dialog, and also the View > Proof Setup dialog for the printer profile?
2. If the test image from the printing service is indeed not tagged with a color space, how sure are you that it's an sRGB image? And how are you treating it for color management purposes when loading it into Photoshop?

P.S. Doing anything with CMYK is probably just adding confusion at this point. Regardless of how the printer in question really operates, if it's a photo printer and they are asking you to upload sRGB files, then the front end is an RGB color process. That's where the focus should stick to resolve what's going on.

Royce, thanks for your input.

The reason for believing that the picture is sRGB is that the pic looks the same in firefox as in Adobe Photoshop when assigning sRGB profile. It also looks more or less the same on my labtob and on any other screen. It's the softproof that looks different ...

Anyway the test image is here:
http://www.pbase.com/ingotkfr/image/140 ... iginal.jpg

When I open it in photoshop, I assign sRGB, then convert to AdobeRGB which basically doesn't change the picture at all.
Then I softproof.

Color settings:
http://www.pbase.com/image/140746379/original.jpg

SoftProof settings:
http://www.pbase.com/image/140746402/original.jpg
(or relatively colorimetric which changes little)

Here's another weird thing:
If I open the picture without assigning a color profile it looks horribly saturated (as expected for an sRGB picture I guess since my work space is AdobeRGB) and if I softproof now, I get a different result (and this one is quite a bit closer to the real print in the greens, at least on my screen, but is overly saturated else!).

A comparison of the things I see in the softproof:
http://www.pbase.com/ingotkfr/image/140 ... iginal.jpg

I'm not sure how photoshop determines what is out of gamut for printing - I suspect that this has nothing to do with the color profile really, because it doesn't seem to change at all. The areas that are greyed out by the gamut warning are the same.

Here's what I get as gamut-warning on the file:
http://www.pbase.com/image/140746535/original.jpg

I hope the pbase links work, it was slow upload.

Edit: I think photoshop issues an out-of-gamma warning with respect to the CMYK profile that is selected in the color settings, but I might be wrong.

Thanks for the links and the further details. I'll take a look and see if anything jumps out...