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regarding "no color management" in Print Tool

regarding "no color management" in Print Tool

2015-04-14 by tracy@...

Love Print Tool (& QTR). Do a bit of Piezography with PT, but recently got an Epson 9890 for larger color prints. Hired a reputable firm to make some custom profiles for me, and printed their target thru Print Tool, using "no color management" and sent them off for profiling. (I verified that the Epson driver also indicated no control being used.)


Not a very good result, and now I'm trying to find the cause.


The symptoms: the light cyan is much too dark; saturation plots (from say full magenta fading to white) show significant bands. (not as if it's an 8-bit issue, not evenly spaced, but the upper 20% will be one shade, and the next 20% is lighter.) In some profiles, a graduated strip of color from full saturation to white, will go from dark to lighter to darker to lighter to darker again, as if chunks had been clipped out and re-arranged. (I see this in reds/magentas.)


I can print out my own profiles using my ColorMunki (which cost about 1/8 of the pro's set up) and have absolutely none of these issues at all. (In fact, I had to do that.)


So: obviously it's me or them, or perhaps their target. I noticed when I saved it out, in order to use Print Tool (I'm on a Mac, so I have to do that) the file is listed as having an sRGB profile embedded. ( I think this is left over from a few years ago when printing without color management was possible by specifying the same profile for the image and printer. Unfortunately, that no longer works.)


I did print out their profile with Adobe's CPU software, and eye-ball it with the PT prints, and they looked the same. (I used PT, because their target was the wrong PPI for their 8x10 needs, and CPU does not allow resizing.)


OK... that's it. I'm wondering if anyone here has some idea what went wrong, or has seen those particular symptoms before. (I really suspect that it's some issue with the target prints I sent,, but I have no idea what it might be...)


Comments welcome. (I can scan a print and post it, if anyone wants to see it...)


Thanks.



Re: regarding "no color management" in Print Tool

2015-04-14 by tracy@...

Thanks, Jeff.

I've posted the profile on my server, here:

and a screenshot of the issue here, on an image-sharing site:

re: the image
A & B point to significant color differents (made all the more interesting bacause the paid profile is overall -lighter- than the other two profiles, yet A and B are darker tones.

C points to the obvious tonal jump

Look in the red column to the right of D and in the B column to see other "tonal banding" issues.

I did drop the profile into ColorThink, and it looks pretty normal at first glance (as do the other two.)

That's why I'm so puzzled...

Thanks again.

solved (I think) ...Re: regarding "no color management" in Print Tool

2015-04-14 by tracy@...

Well, I believe I found the issue: the paid profiles native rendering intent is Relative instead of Perceptual.

The ColorMunki, and all the Epson and other third-party supplied profiles have a specified rendering intent of Perceptual, not Relative Colormetric.

When printing either as relative or perceptual from a native perceptual profile, the colors are correct and there is no sudden jump in gradation patterns. ("C" in the above case.)

When printing with the paid profile (which is native relative instead), using a perceptual intent works fine (no banding; smooth gradations; proper color) but when selecting relative colormetric during printing, the banding and off colors appear.

I'll admit to not completely understanding why relative/relative doesn't work, so if someone would care to explain, I'm eager to learn.

Meanwhile, I'll ask the supplier of the paid profiles to re-do them with a perceptual intent.

Thanks, folks.

Re: solved (I think) ...Re: regarding "no color management" in Print Tool

2015-04-14 by tracy@...

I agree, Jeff - I've never seen it before either, and I'm well over a decade into this stuff.

I've intentionally not mentioned who supplied the profiles to me, but suffice it to say that they should be -THE- go-to company for providing them.

We've been on the phone and they're looking into it, and we've got some other tests to run, so I'll give it some time before I bother anyone on LuLa.

I'm starting to wonder if it's the latest manifestation of the usual mix of Apple/Epson/Adobe issues.

I tried converting the colorspace of the image using that profile, one with RC and once with perctp, and then layering them in photoshop, with the "difference" blending mode. That does indeed show the problem fairly clearly with these new profiles vs other, older ones.

If we can't figure it out, I'll head over to LumLand and see if they have any ideas. Thanks for that suggestion.

More here when/if I find out something new.

Re: [QuadtoneRIP] Re: solved (I think) ...Re: regarding "no color management" in Print Tool

2015-04-15 by Kirk Thibault

I opened your ICC profile in ColorThink and made a 3D graph of the gamut volume. There is definitely some funkiness going on in the magenta region - view it in wireframe at 5% steps. There appears to be compression of the wireframe mesh in the darker tones from purple through red and there are some distortion in the area of the darker magenta tones.

Screenshot:

http://kirkt.smugmug.com/Photography/Link-Share/i-kDhZNN3/0/O/Ep-ScreenShot.jpg

Perhaps when your image gets converted from its working color space to the printer profile space, the relative colorimetric intent, bringing out-of-gamut values to the surface of the gamut volume but leaving in-gamut colors more or less in place, exposes this profile funkiness. Perceptual rendering intent during conversion should scale inward all of the color values so that the most out-of-gamut colors get mapped to the volume surface - this will keep color relationships intact and, if the profile funkiness is something that is most prominent at the volume surface, will likely affect only a small number of pixels. Maybe this would explain why you are seeing the problem with relative colorimetric versus perceptual intent, because the rel. col. intent exposes the profile funkiness more effectively than perceptual.

Just a guess - I have admittedly crossed way over the boundaries of my color knowledge.

kirk
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On Wed, Apr 15, 2015 at 12:41 AM, jeff.grant@... [QuadtoneRIP] <QuadtoneRIP@yahoogroups.com> wrote:

Using i1Profiler, it isn't an option, unless I've missed something. I wonder what they used to build your profile. I checked a few profiles and they are all Perceptual.


Re: solved (I think) ...Re: regarding "no color management" in Print Tool

2015-04-16 by tyler@...

aside from whether or not there is something wrong with your profile.. the default intent sometimes built in shouldn't really be a problem. It's questionable whether or not many apps honor it, and the choice and decision what intent to use is always yours, using the apps most of us use here. Hope that makes sense. Additionally, there is often some visual discontinuities with relative vs perceptual in colors at the gamut boundry, since they may be chopped. I've seen other discontinuities with colormetric as well, depending on the profile, and image colors. Percpetual moves all that into gamut and smooths those transitions.


---In QuadtoneRIP@yahoogroups.com, <tracy@...> wrote :

Well, I believe I found the issue: the paid profiles native rendering intent is Relative instead of Perceptual.

The ColorMunki, and all the Epson and other third-party supplied profiles have a specified rendering intent of Perceptual, not Relative Colormetric.

When printing either as relative or perceptual from a native perceptual profile, the colors are correct and there is no sudden jump in gradation patterns. ("C" in the above case.)

When printing with the paid profile (which is native relative instead), using a perceptual intent works fine (no banding; smooth gradations; proper color) but when selecting relative colormetric during printing, the banding and off colors appear.

I'll admit to not completely understanding why relative/relative doesn't work, so if someone would care to explain, I'm eager to learn.

Meanwhile, I'll ask the supplier of the paid profiles to re-do them with a perceptual intent.

Thanks, folks.

Re: [QuadtoneRIP] Re: solved (I think) ...Re: regarding "no color management" in Print Tool

2015-04-16 by tracy@...

Thanks for that. You are likely entirely correct in that. What confused me was that I could switch between Perct and RC using other profiles (Epson, my own, paper mfgrs) and print the same image, and never see the compression "banding".

So I assumed that it had to be something peculiar to the paid profiles, and apparently Kirk (above) has pointed the way to seeing it.

(I have intentionally left that company's name out of this, because it's a name everyone would recognize and respect instantly, and I don't want to taint it by mistake, much less look a fool if the issues turns out to be something I did.)

NOW... I'm off to try Kirks ColorThink representation of that profile.

Re: [QuadtoneRIP] Re: solved (I think) ...Re: regarding "no color management" in Print Tool

2015-04-16 by tracy@...

Kirk - first, thanks for the time and effort you put into this. I see that I should have looked more closely when I popped into ColorThink, and it looks to me like you've hit the nail on the head. As soon as I finish this reply, I'll be taking a closer look myself.

I wonder what would cause that mis-read? Could the illumination source of their hardware be fading?

I just ordered a i1 Photo Pro 2 kit from BH, so I can see what's up for myself. Should be here early next week.

I suspect that your analysis is entirely correct, Kirk, and again: I appreciate your time in providing it.

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