RE: Photoshop 6/7 problems with OptiCAL Monitor profiles
RE: Photoshop 6/7 problems with OptiCAL Monitor profiles
- Subject: RE: Photoshop 6/7 problems with OptiCAL Monitor profiles
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Sat, 15 Feb 2003 14:46:00 -0600
John <email@hidden> wrote:
>
It sounds like an OptiCal-created D-65 monitor profile will lead to
>
Photoshop incorrectly modifying data sent to the display - so the image
>
looks "more blue" than it should, right?
The grayscale is not affected by this problem, which may be why it has gone
undetected for so long. The problem is that the chromaticities of the
phosphors that the CMM uses are wrong. So the color error becomes greater as
a color is farther away from the grayscale.
>
And should this behavior should be the same on Mac & Windoze?
Yes, the bad profile will cause problems on any software that uses it (e.g.
any ICC based CMM, regardless of platform). Note that the profiles I
examined were made from Windows versions of OptiCAL. I do not know if the
Mac versions also have the problem. But I could find out if someone could
send me a profile made with a Mac OptiCAL along with the corresponding
OptiCAL Information panel numbers.
>
What if I have OptiCal calibrate to "native" white point?
>
(after using PreCal to set luminance, and with no RGB gun control, a
>
reported white point of about 5500K)
You will have the problem whenever the monitor's white point chromaticity is
different from the D50 chromaticity (x = 0.3457, y = 0.3585).
>
Is Photoshop doing an adaptation based on incorrect data here too?
Whenever the white point tag is not D50, the problem will occur. The reason
why it works when the white point tag *is* D50 is that adaptation is not
needed in that case, so OptiCAL's "missing" adaptation does not matter.
--
Bruce J. Lindbloom
email@hidden
http://www.brucelindbloom.com
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