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Author Topic: ICC printer profile problem  (Read 4026 times)
tony field
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« on: October 16, 2007, 09:40:41 PM »
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I am still having problems developing a good profile with the Greta Macbeth i1 pro sytem.  In particular, the current problems are with the Canon Pro 9000 printer.  Prints are "too dark/contrasty".  To the eye, compared to the screen, the images seem to be the equivalent of about 1/2 stop "underexposed".

I understand that the generated profiles should yield "almost perfect" results with only minor tweeks needed in the profile editor.  In my case, "large" profile changes to brightness is needed.  Obviously, I am doing something wrong or have missed some critical step.

This is the process I used:

--- printer configuration ---
The print calibration uses the i1 TC 9.18 Testchart

color handling: Photoshop manages colors
printer profile: generated by Greta Macbeth i1
rendering intent: perceptual
canon printer preferences color/intensity: manual
canon manual color adjustments: none
canon print quality: custom (fine, diffusion)

--- monitor calibration ---
white point: 6500K
gamma: 2.2
luminance 108.4 cd/m2
min luminance: 0.4 cd/m2

ambient light: 4200k
illuminance: 21 lux

--- print viewing ---
viewing illuminance: 1000 lux (can vary between 600 and 1900)
lamp temperature: 5500 K (fluorescent)

The screen image is has good colour with appropriate contrast. Printing with the new profiles yields a darker than expected image and, because of the extra saturation, seem contrastier. Of course, the profiles can be edited to adjust the output image.

To approximate the print on-screen, I can adjust the Curves of the photoshop image. Viewing the print and screen as carefully as possible while adjusting the curves, the amount of darkening is quite substantial - the curves input/output numbers are

input: 150
output: 130

If I were to guess in terms of camera exposure, it almost looks as though the print is under-exposed by about 1/2 or more f-stops compared to the screen :-). This is under my 5500K fluorescent viewing lamp with more than adequate intensity.

Soft proofing (CTL/Y) does not show the darkening effect - only minor gamut and tonality shifts are seen and this is reflected in the "proof image" on the "print" screen. Since Photoshop is handling the colour management, the print driver preview is, as expected, off-colour and intensity.

I don't know if it is significant - screen profiles are loaded by the Windows ICC Colour Loader. No other loaders are used.

I also examined images from a friend that looks excellent on her apple computer and looks "virtually identical" on my microsoft system. This indicates that my screen calibration should be quite good (or hers are equally as bad as mine :-)

I am using four test images: my personally prepared "velvia like" colour image with many colours, two grey scales and a colour rainbow. The second and third images are of ladies with different skin tones. The fourth image is the Canon-provied 1Ds-III portrait sample (young lady with pearls and a white dress).

I hope these full sized and large (4mb or larger) files are appropriate. The can be retrieved here if you wish to look and certainly comments about the image choice would be appreciated:

http://tphoto.myphotos.cc/noise/ctest01.jpg
http://tphoto.myphotos.cc/noise/ctest02.jpg
http://tphoto.myphotos.cc/noise/ctest03.jpg
http://tphoto.myphotos.cc/noise/ctest04.jpg

This is getting frustrating...

any additional ideas.??
« Last Edit: October 16, 2007, 10:14:59 PM by tony field » Logged
pherold
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« Reply #1 on: October 17, 2007, 01:44:18 PM »
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I am still having problems developing a good profile with the Greta Macbeth i1 pro system.  In particular, the current problems are with the Canon Pro 9000 printer.  Prints are "too dark/contrasty".  To the eye, compared to the screen, the images seem to be the equivalent of about 1/2 stop "underexposed".

Tony,
You've done a great job of troubleshooting this.  You've covered all the right bases.  A couple of ideas:
-  You don't mention if you've gone back to square one and tried again from the start with a new target, new measurement reading etc.  You probably have, but just in case, that's the thing to try.  Sometimes with these things we can't really find a reason why, but re-doing it seems to work the second time.
-   When you are comparing your print to your softproof on your screen, will a blank, white piece of your printer paper match the white of a blank document in Photoshop?  That would be a confirmation of whether your lighting situation is a good match for your screen calibration.
-   You might try doing your color management in the printer driver instead of Photoshop.  That's usually a no-no, but it's worth a try in this case.  Sometimes there are bugs in the way these software packages interact with each other.  Take your custom profile and put it in where the driver can access it, and have the driver use that profile.  Then, set Photoshop to "let printer handle colors" or turn color management off.

-Pat Herold
CHROMiX tech support
« Last Edit: October 18, 2007, 12:51:33 PM by pherold » Logged

-Patrick Herold
  Tech Support
www.chromix.com
Geoff Wittig
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« Reply #2 on: October 17, 2007, 06:18:52 PM »
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I don't mean to be insulting your intelligence; it's obvious that you're very knowledgable about color management and soft proofing. Here's my experience with this problem. My prints also looked a good half stop or more darker than the on-screen appearance, no matter how carefully I profiled or soft-proofed. When prints are carefully examined with bright light, the shadow detail is actually there; it's just hard to see under more typical lighting. Transmitted light from a monitor is fundamentally different from reflected light off a print. The appearance on-screen is a much closer match to the print if you apply a white background in Photoshop and reduce the size of the image enough to show a generous amount of this background. Suddenly the photo looks a lot darker, and closer to the print, especially one in a white matte. If you doubt how much this affects perception, just switch to a black background and note how much lighter the image looks. Charlie Cramer emphasized exactly this point at the (excellent!) digital printing workshop last weekend at Michael's studio.
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tony field
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« Reply #3 on: October 17, 2007, 08:36:28 PM »
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... it's obvious that you're very knowledgable about color management and soft proofing.

Wish that were true.  This is my first go-around with both screen and printer profiling.  All of this is new to me.

Quote
The appearance on-screen is a much closer match to the print if you apply a white background in Photoshop and reduce the size of the image enough to show a generous amount of this background.

I tried this on various images.  Those that were darker in overall tone - women on a black background, scenics with lots of darker green trees, some performing arts shots - did seem slightly better for comparison but no where near enough to make up for the difference.  Higer key images - women on a white background, snow shots, some scenics - showed no visual difference.  Still, the prints were darker than the screen by a long shot.

It was worth a try....
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AaronPhotog
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« Reply #4 on: October 17, 2007, 11:32:13 PM »
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Tony,

When you print the target to measure, are you setting it to
"no color management?"    

If so, try printing out a standard color ramp image (showing steps of red, blue, green, cyan, magenta, yellow and gray, all progressing from light to saturated), again, with "no color management."  If the colors are significantly off, and your target also is significantly off from the way it looks on screen, then you may have a hardware calibration problem.  You may need to work on getting the inking adjusted so that the ramp and target are closer to what you see on screen so that your profiler can properly interpret the patches and make the adjustments that will result in a close match.  You shouldn't have to darken your screen.  I'm not familiar with Canon's drivers, but I've had to make such adjustments for my Epson 3800 in order to get clean and accurate colors.  I was otherwise getting dark and muddy colors as a result of overinking cyan and magenta.  With the Epson driver there are sliders that allow you to reduce (or increase) the ink loads individually.  When you do that, though, it means you have to convert the image to the profile you made for that paper and print from the printer driver, with Photoshop set to either "no color management" or "let printer manage color."

Making sure you have selected the right paper type can make a slight difference in ink load, so you may want to experiment with that and rendering intents as well.
« Last Edit: October 17, 2007, 11:33:06 PM by AaronPhotog » Logged

Aaron Dygart,
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eronald
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« Reply #5 on: October 18, 2007, 04:38:08 AM »
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In my experience, luminance issues when profiling prints are usually non-issues: The screen profile can be the culprit, indeed some years ago the i1 display was a major offender here, but AFAIK that's been fixed. In any case you should explore reprofiling the screen with different software. A cousin of the same issue is the fact that most screens (except those with internal sensors and servo-ccircuits) will have importance luminance variations as they warm up. On a related note, if using an Epson, on a Mac system, make sure to set it as the default printer in the Printer Manager *before profiling* or problems may ensue. Prints made with a canned profile should already be in the ballpark.

Edmund
« Last Edit: October 18, 2007, 04:40:34 AM by eronald » Logged
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