Re: Weird Color Behavior?
Re: Weird Color Behavior?
- Subject: Re: Weird Color Behavior?
- From: Roger Breton <email@hidden>
- Date: Sat, 21 Feb 2004 23:38:19 -0500
>
With all due respect, I'd like some of whatever it is you've been
>
smoking. Try doing an absolute colorimetric conversion from Adobe RGB
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to your 5000K monitor profile, then tell me in what way it's useful.
Of course it's not very useful in itself but it's fantastic to illustrate
RGB working spaces! Now, if you tell me that's how blue an sRGB document
would be displayed on my D50 calibrated monitor with an option to display
the document white absolutely matched to my monitor then I'd say no thank
you, of course. And I have to confess that this partly does what I'm after,
thank you. The way Photoshop normally display an RGB document now is that it
manages all the document colors except the document white. But the way an
AbsCol conversion from AdobeRGB to my D50 monitor profile comes out is that
all colors are now exagerately blue. I'll do some measurements and compare
with what I expect those colors to display.
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The object of the exercise is to get the working space to display as
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close as possible to identically on everyone's monitors.
Hmmh?
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If you look
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at the monitor, your eye adapts to monitor white, whether or not you
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want it to.
I don't debate that.
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Hence a relative colorimetric conversion from working
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space to monitor space lets us all see the same thing irrespective of
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whether we prefer to calibrate our monitors to 5000K, 6500K or any
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points north, south, or inbetween.
I agree that's the intent. Now, whether this actually 'lets us all see the
same thing' irrespective of our preference for monitor calibration I am not
sure? My humble experience suggests otherwise. The example I have in mind if
the display of a Macbeth ColorChecker II, in Lab, on a D50 and D65
calibrated monitors, side by side. I am sure you've done this experiment
once but would you say that the image appears the same in both cases? Maybe
you will say that we don't all use two monitors we simultaneously view
images side by side, at different calibration, and therefore it's a moot
issue. Maybe I should shut up or stop taking that stuff I've been taking <?>
and simply accept it as a 'fact of digital life', but I have a hard time
with the idea that Photoshop and our eyes are combining into making us 'all
see the same thing' when I can the real difference between different monitor
calibration is plain to see, there is a limit to what our eyes will actually
adapt to, no? In a side by side comparison, can you say that you really see
the 'same thing'?
>
This is not "making an exception for the document white" - it's
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acknowedging the simple fact that our vision is automatically biased
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by our monitor white point, and exploiting same fact of life to make
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sure that when I send you a perfectly neutral Adobe RGB image, you
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don't immediately conclude that it has a blue cast and screw it up.
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That's what would happen if you used absolute colorimetric
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conversions for display.
I'll buy that.
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"Blue" and "yellow" are not overstatements! Do the conversions
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yourself if you don't believe me-we aren't talking "slightly bluish"
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and "slightly yellowish."
I intend to take measurements soon of this phenomenon because I've been
talking with some people on the sci.color.engr newsgroup and I have a
feeling that Photoshop is exagerating the display in those mismatch
situations. I just deeply piqued my curiosity, what can I say.
>
But what could conceivably be the point of building an imaging system
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that displayed white as something other than white, outside of
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proofing situations where you want to see the impact of the paper
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color?
Well, the whole point of my reflexion, and thank you for walking this route
with me, is th whole notion of white. I thought I had a clear mental picture
of how white is modeled and processed in the ICC model between whathever
source and an output profile. But it's how white is handled between the
working space and the monitor that bugs me. I was taking certain things for
granted and all of a sudden I felt I stood on shaky grounds. So that's why I
felt the urge to reach for help. This being said, the point of an imaging
system that displayed white as either 'yellow' or 'blue' would serve the
purpose of developping a sensitivity that all soft proofing is never to be
taken absolutely. Yes, converting relatively to it is probably the only
sensible way to do it but, to me, that ought to be explicit rather than
implicit. Have you never felt that faced with the multiplicity of existing
papers today all exhibiting countless nuances of 'white' that 'white' has
become an oxymoron? What is white: PCS white? It's an ideal that does not
exist. Yet, we all refer to it as 'white', the perfect non-selective
diffuser.
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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