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Author Topic: Occasionally plugged up shadows?  (Read 1460 times)
Larry Heath
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« on: July 04, 2013, 05:12:07 PM »
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OK, having a bit of problem with my color management, not all the time, just occasionally.

So, I print on an Epson 9880 using Epson inks with photo black, edit with LR 5 and PS CS6. I do this on a Windows 8 machine using a Dell U3014. All of this has been profiled using an X-Rite Color Munki photo.  All papers have profiles built etc. The monitor profile is set at 80 candles and 6500K, I view prints under 6500K illumination of approximately 4500 lumens of output at about 4 feet above the prints.  I had this same issue on an older system as well, Win 7 with dell monitors all profiled etc.

I have read about the “dark print” issues some have and this is not really that, well I don’t think so, as most prints are as close to WYSIWYG as one could wish. Once in a while I get a print that is perfect in the highlight and mid tones, but the shadows are all plugged up, just yucky blacks with no gradation. On the monitor there is nice separation in the shadows and other prints with the same type of shadows print perfectly.

So, as far as I can see all my ducks are in a row, except once in a while I get a print that just will not reproduce the shadow gradation that I can easily see on my monitor and which reproduce quite nicely in other similar files using the same workflow. This seems to happen randomly on all the papers I print on, and not on any single paper, there just doesn’t seem to be any common denominator to be found.

Does anybody have any comments or suggestions that might point me in the right direction to address this somewhat vexing little issue?
Thanks Larry
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Schewe
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« Reply #1 on: July 04, 2013, 05:32:31 PM »
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Do the same images look plugged up when you soft proof?
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Larry Heath
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« Reply #2 on: July 04, 2013, 05:41:13 PM »
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No that is the point. They look just fine using soft proofing. The majority of the time prints match the soft proof very well.

Later Larry
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digitaldog
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« Reply #3 on: July 04, 2013, 06:26:13 PM »
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Could be an issue with a contrast ratio miss match. Having control over black to control this via calibration is useful, having a suite of them based upon each paper is really useful! To do that well, you need a 'smart monitor', something like Eizo/Spectraview with full control over black via the electronics in the panel.
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Andrew Rodney
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Ernst Dinkla
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« Reply #4 on: July 05, 2013, 03:21:15 AM »
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If it happens on all papers and on rolls and sheets, then I would suspect some irregularity in the ink feeding system. A software glitch that always selects another media preset that gives a higher ink load than the compatible one is unlikely. PK used for glossy papers I assume, on matte art papers the PK may show more dotgain than an MK ink.

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Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
December 2012, 500+ inkjet media white spectral plots.
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Larry Heath
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« Reply #5 on: July 05, 2013, 10:29:00 AM »
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Hello Ernst,

Thanks for the comments.

I have been kind of thinking along your line of reasoning, i.e. higher ink load. To for stall the concern of paper/ink mismatch I print only on papers compatible with the PK ink on this machine, so I don’t think it is an ink paper mismatch.

Let me add a second part to the puzzle, which I neglected to point out before, but now after Ernst’s prompting seems appropriate. I edit on one machine and transfer the files to a laptop which I use to drive the printer with, which is at another site. As best as I can tell, I am pretty sure all the paper profiles on both machines are the same and latest incarnations. The one thing here is that the laptop uses PS CS4 as opposed to CS6 on my main work machine, could this be an issue?   Am I correct in my understanding that color management is supposed to help control color reproduction problems in cross platform situations like this?

Here is the final quirk I’ve noted, as I operate more or less in a vacuum i.e. no formal training and no experience outside of what I have discovered on my own, can anyone tell me if printing from a windows CS4 platform normally pops the print driver/setup dialogue twice? Which I suspicion may be the culprit in all this.

So let me step you through this,
1 open print file (CS4 laptop)
2 select print from PS File menu
3 select all necessary settings including PS manages color making sure printer color management is off, black point is on and I have selected the correct paper profile, correct paper type, etc., etc. Hit print and off things go, well sort of.

Here is the thing that I don’t know/understand if it is standard behavior in a Windows/CS4 environment for PS/Epson print drivers or which could be the root my issue. As soon as I hit print in previous step (3) I get the basically same dialogue popup asking for all the same info again. I check everything a second time and hit print, and now it actually proceeds to print. Is this one of those are you “really sure” you what to do it this way sort of software “features” peculiar to CS4, or is this something that could be the root of my sometimes issue, i.e. a double profile, but that only seems to effect the black ink and only sometimes?

Could this be where I seem to sometimes get what seems a double dose of black ink?

Further I just checked on my main work unit printing from CS6 doing a test printing to the 9880 as a null printer, and I don’t get this same two-step hokey pokey on it? Curious’er and curious’er!

Well I suppose now that I actually have some free time I should actually go make some prints that I can collect a check for, instead of trying to scratch this small annoying intellectual itch, which in the main seems of little practical significance.

Later Larry
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Jim Kasson
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« Reply #6 on: July 05, 2013, 11:55:36 AM »
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Does anybody have any comments or suggestions that might point me in the right direction to address this somewhat vexing little issue?

When faced with intermittent problems like this, I like to create something constant in the output. On thing that might work for you is to have a step wedge that you put near the actual image, but far enough away that it will be covered by the mat, or can e trimmed off. When you find a bad print, you can look at the step wedge and compare it to that of a good print. It would be more precise if you could take readings with a densitometer (available used on EBay for not too much money, and a handy thing to have around) or a spectrophotometer (more expensive, more versatile, but takes more color knowledge to use). However, if the effect you're looking at is not too subtle, and it sounds like it's not, you could just put the two step wedges next to one another and eyeball them.

If the wedges are the same and the prints are different, there is some image-dependent mischief going on. If the wedges are different, there is an intermittent problem in your printer, or, less likely, in the software chain the image goes through.

To keep things simple, the wedge could be just gray.

I have seen blocked shadows that resulted from nozzle clogs.

Jim
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Larry Heath
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« Reply #7 on: July 06, 2013, 10:58:29 AM »
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Hi Jim;

Printing the step wedge seems a very good idea; I will incorporate that for a while. I have a PhotoMunki spectrophotometer that I can measure the printed step wedge with if I get a flyer.

I would be inclined to think that it isn’t a clogged nozzle.  I print a nozzle check every day on this printer with Harvey Head Cleaner and I haven’t seen a bad one in going on nearly a year since I first got the printer, of course this doesn’t preclude having a clog during a print.

Thanks for the suggestions.

Later Larry
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Tim Lookingbill
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« Reply #8 on: July 06, 2013, 11:39:00 AM »
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You may have to rule out "out of gamut" clipping in the shadows if that hasn't already been addressed here.

You haven't shown us what kind of images this clipping occurs and on what type if not all papers which the grayramp test even if it passes may not address gamut clipping in relation to certain paper types and whether the profile used can handle it. There's so many variables to address here.

You may need to test different rendering intents.

Even on my cheap Epson "All In One" I get pretty good matches down into the shadows with "Printer Manages Color" on Ultra Premium Glossy on a wide range of images but there are some polarized looking river shots of deep, rich bluish clear water with lots of rock detail made up of various hues of deep turquoise transitioning into cobalt blues and cyans that I think are going to turn to mud and come out looking fine.

Switch to Epson Presentation Matte and the detail is rendered in chalky looking blobs of bluish black. Of course I don't Soft Proof because there's no custom profile.

Your particular hue of shadow black in any particular image brought out in editing or straight from the camera may not be one that's factored into the custom ICC printer profile for that particular paper. Soft Proofing isn't perfect and fool proof (pardon the pun).
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Larry Heath
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« Reply #9 on: July 06, 2013, 03:25:57 PM »
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Ok here is an example of an offending file. This started off life, for me at least, as a Library of Congress TIFF file. Which I think could possibly be another clue to the bigger issue here. I seem to remember reading somewhere that TIFF’s contain embedded ICC profiles, true or not? Now I can’t say for sure but I don’t think I’ve ever printed this file directly as a TIFF. So could this be part of the problem?



The offending areas are in the lower left corner and left of the white line running down the aisle and on the table with tools on it. Now I realize this is a challenging file in these areas to say the least and yes indeed there are and should be blacks in this area but as I think you can see even in this JPG file there is a lot of detail in the bricks and table that just all turn Dmax black. This is when printed on BC Crystal Glossy canvas and is just barely better on BC VibranceGloss photo paper. I might add this is with profiles built for these papers and optimizing the profiles using this file in particular, as a TIFF file by the way, with or without attached ICC profile from the Library of Congress who knows, as per PhotoMunki’s file type needs for profile optimization.

Well I’ve figured some of it out. Thank you TIM! But now I have a different issue.

It is indeed an out of gamut problem for the printer; well we kind of knew that before, but now I see PS was trying to tell me. It was right there on the darn screen, only it is so subtle on the screen that you can’t easily see the gamut warning until you turn gamut warning OFF! Apparently the out of gamut warning, which was set as light gray, appears as false detail and lightens the apparent values on the screen. Even after editing PS preferences for the Out of Gamut indicator color it really is not at all apparent in this file when PS is displaying it on screen. In fact all the out of gamut indication does is make the damn file look better on screen, well at least in the dark shadow areas. Go Figure!

Apparently for reasons unknown the onscreen gamut warning in CS6 doesn’t work quite as well as it should, at least for this file. I can set the preferences to any color I wish for gamut warning color and even if I magnify offending areas to an individual pixel level at 3200% all I see is a shift from one shade of dark gray to another very slightly different shade of dark gray when I turn gamut warning in soft proofing on and off.   Not a single pixel changes to the garish bright yellow I now have it set to. What’s up with that?

So once again thanks Tim for getting me to look really really hard at the gamut warnings provided in soft proofing, they apparently do work, just sometimes they won’t jump up and smack you upside the head like one would imagine they should.

Anybody know any of the programmers at Adobe that might like to look at this?
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Tim Lookingbill
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« Reply #10 on: July 06, 2013, 04:36:29 PM »
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Not a good file to test shadows especially when it's been converted to sRGB by LOC you downloaded it from.

Those shadows should plug up to black in that area because the blacks are out of gamut. Too much cobalt blue which inkjets can't reproduce the densities for so it substitutes black to provide perceptually pleasing transitions into lighter tones in the image.

I took shot of my display and processed in Raw to lighten the image to demonstrate. The shadows don't look that blue on my display but my camera's sensor was picking up on it even though I couldn't see it with my eyes. The image states the blue bias RGB numbers as read from Photoshop's Info Palette in the original sRGB image dragged and dropped from this thread.

You should use a really good and stable print test target which there are plenty to choose from online.
« Last Edit: July 06, 2013, 04:40:20 PM by Tim Lookingbill » Logged
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