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Author Topic: Correctly showing color on monitor for a document converted to output profile  (Read 2026 times)
darlingm
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« on: March 22, 2014, 11:13:56 PM »
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Want to make sure I'm not missing a setting.

1. Create ProPhotoRGB document, fill it with white (RGB 255/255/255, LAB 100/0/0).
2. CONVERT (yes, convert) to your favorite printer profile, using your favorite rendering intent.

I would expect to see the "white" on my monitor change, to match the whitepoint given using that profile and rendering intent.  But, the "white" doesn't change on the monitor.

If I set "Edit->Color Settings->Conversion Options->Intent" to "Absolute Colorimetric", it shows the LAB value (in info panel, color picker) of the whitepoint from using that profile and rendering intent, but still doesn't affect how it's displayed.

It seems to me like Photoshop is stuck on scaling the document profile's whitepoint to the monitor's whitepoint, without a way to tell it to stop.  Almost like it's stuck using relative colorimetric transforming from the document profile to the monitor profile, with the monitor profile saying its whitepoint is LAB 100/0/0, without a way to say I want the conversion to the monitor profile to be done on an absolute colorimetric basis.
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Mike • Westland Printworks
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http://www.westlandprintworks.com • (734) 255-9761
darlingm
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« Reply #1 on: March 22, 2014, 11:26:59 PM »
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Why?

I use QImage to print.  But, much to the dismay of its author, I only use it for layout - not resizing, color management, or sharpening.  (And, also because Photoshop doesn't allow printing without color management anymore.)  I want the process to be fast.  I don't want to wait for my computer to recalculate resizings, color transformations, or sharpening it's done before.  And, I don't want to be able to make a mistake on which rendering intent or amount of sharpening I used in the past.

So, I prepare a "ready to go" TIFF file for QImage.  I do the enlarging and sharpening in Photoshop (or PhotoZoom Pro if needed), and save as a gigantic file.  I convert to the output profile, using the rendering intent I want to use.  Then, in QImage, I turn off all color management, interpolation, and sharpening.

My time is limited, and storage has become very cheap.  Others may strongly disagree, but I'd rather have a 1GB TIFF file sitting around ready to be spit to the printer and know for sure it's going to come out just like it did last time, and without having to wait for my computer to re-render it.  (A 4TB drive is now around $185, so a 1GB file costs $0.045 to permanently store, plus backup costs - yes only 4.5˘)

I operate on-demand for many clients, and need reprinting to be as time efficient as possible.  And, most of my work is artwork reproduction which starts out at 400ppi at original size anyway, so I'm already working with gigantic files.

So, I'm constantly converting to output profiles.  And, what I'm considering a "bug" or at least a missing "feature" causes lots of problems then, because it isn't displaying accurately.
« Last Edit: March 22, 2014, 11:29:51 PM by darlingm » Logged

Mike • Westland Printworks
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BartvanderWolf
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« Reply #2 on: March 23, 2014, 05:04:36 AM »
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Want to make sure I'm not missing a setting.

1. Create ProPhotoRGB document, fill it with white (RGB 255/255/255, LAB 100/0/0).
2. CONVERT (yes, convert) to your favorite printer profile, using your favorite rendering intent.

I would expect to see the "white" on my monitor change, to match the whitepoint given using that profile and rendering intent.

Hi,

Why do you expect that? In a color managed environment the document that was converted to the output profile, will be 'reconverted' to your display profile! Only when you soft-proof, with some assumptions for e.g. paper white, you will get something that 'somewhat' resembles the output.

Cheers,
Bart
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Czornyj
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« Reply #3 on: March 23, 2014, 05:33:07 AM »
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Use soft proofing with the same profile you used while converting the document, and turn on paper white simulation.

A better, more accurate solution is to create multiple calibrations to multiple wtpt's, that will mimic the wtpt of the paper in a target environment - you can do achieve it with NEC P/PA, Spectraview II or Multiprofiler software.
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D Fosse
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« Reply #4 on: March 23, 2014, 06:11:24 AM »
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Yes. The key here is the calibration target white point.

The display white point should be a visual match to paper white (under specific conditions).

To get an even better match, you should also bring the black point/contrast into the equation, and specify a matching calibration target for that.
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hugowolf
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« Reply #5 on: March 23, 2014, 01:56:53 PM »
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And if it didn’t show RGB(255,255,255), wouldn’t you expect the printer to try putting down an off white ink mix? (It would certain solve some gloss differential problems.)

Brian A
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darlingm
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« Reply #6 on: March 30, 2014, 09:21:59 PM »
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Why do you expect that? In a color managed environment the document that was converted to the output profile, will be 'reconverted' to your display profile! Only when you soft-proof, with some assumptions for e.g. paper white, you will get something that 'somewhat' resembles the output.

Because it can only do that document profile to display profile conversion, using a specific rendering intent.  And, in Color Settings, I'm telling Photoshop to use a default of Absolute Colorimetric.  But, displaying appears to be hard coded with an intent and ignore that setting.  If they don't want for displaying to use the given default intent, there should be "display intent" setting.  It shouldn't be hard coded.

But, I found I can force it to act how I want it to by having the document in the output profile, and converting it back to ProPhoto RGB using absolute.

Use soft proofing with the same profile you used while converting the document, and turn on paper white simulation.

A better, more accurate solution is to create multiple calibrations to multiple wtpt's, that will mimic the wtpt of the paper in a target environment - you can do achieve it with NEC P/PA, Spectraview II or Multiprofiler software.

I'll admit I hadn't tried soft proofing with the same profile the document is already in.  I improperly assumed that wouldn't do anything.  And, yes, an even better monitor and color management software is on the list.  Smiley

And if it didn’t show RGB(255,255,255), wouldn’t you expect the printer to try putting down an off white ink mix? (It would certain solve some gloss differential problems.)

I wouldn't expect that.  If the document is in the output profile and has RGB 255/255/255, printing it without further color management sends the RGB 255/255/255 values to the printer, leaving bare canvas white.  When the info panel is showing me RGB 255/255/255 is LAB 97/0/2 (because I have absolute intent as default in Color Settings, and that's the LAB whitepoint of the output profile I'm using), I'd like it to display LAB 97/0/2 on the display.
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Mike • Westland Printworks
Fine Art Printing • Amazing Artwork Reproduction • Photography
http://www.westlandprintworks.com • (734) 255-9761
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