Re: MS Color Control Applet
Re: MS Color Control Applet
- Subject: Re: MS Color Control Applet
- From: Roger Breton <email@hidden>
- Date: Thu, 29 Jun 2006 09:37:45 -0400
Hi Marco,
> The ColorSync utility scales both white and black points when graphing a
> profile: that way, AdobeRGB does indeed end up being completely encompassed
> by ProPhoto RGB, because the AdobeRGB color space gets slightly offset by
> the scaling, enough to move it all the way inside ProPhoto RGB.
OK.
> But a D50 white point *is* different from a D65 white point, and differences
> exist among black points. To be "Spockian" about it, it would seem logical
> that these differences should be adequately represented when comparing
> profiles.
Well, I'm confused here. Because, as you recall from a recent thread on this
List, Adobe changed the way it interprets the white point when dealing with
RGB working spaces. Before CS2, I believe Photoshop *does* show a D65 white
point as bluish on a D50 calibrated monitor. But not anymore, having to do
with the change in ICC specs to the present v4 version.
In absolute terms, as far as representing or graphing each respective RGB
gamut in 3D like ColorThink does, I tend to think that each white point
should coincide to agree with v4 specs. Personally, however, I prefer to
show them with having distinctive white point locations reflecting the fact
that D65 is bluish and D50 is not as bluish (notice I did not say yellowish,
even though that's how direct sunlight appears to our vision system, as far
as I can observe and discuss with other color folks).
>> In fact, ProPhoto does encompass Adobe RGB.
I would expect, like I said above, that ProPhoto to fully enclose AdobeRGB
except at the very top where I would expect the two white points to
coincide, at L=100, if I interpret the intent of the new specs well. At any
rate, all the white points of any RGB color spaces are considered as PCS, by
definition of the ICC specs (that was the intent in v2 specs but that is the
mandate in v4 specs), that is no matter what the calibrated white point of a
monitor, in the monitor profile, the white point has to be D50. Period. Such
that whathever the chromaticity of the RGB space, RGB=255,255,255 is forced
to Lab 100,0,0. In Photoshop, this translates to ProPhoto D50 white point
being slapped onto a D65 calibrated monitor white point as is (like Bruce
setup, if I recall), for example, and an AdobeRGB D65 white point being
slapped onto a D50 calibrated monitor white point (like my setup). As long
as the user leaves the Simulate Paper White alone, all colorimetry to the
screen is *relative* (that's not the same across all editing packages,
however). Further, if you're considering someone designing strictly for the
web, the question of soft proofing never comes into the equation. In this
application, absolute colorimetry to the screen is an anathema. (The same as
relative colorimetry not existing in GMG ColorProof, everything is absCol by
definition, there is no interface to change that -- in their 4D proprietary
world, which is kind of a nice place to be).
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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