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: JWL <email@hidden>
- Date: Sat, 15 Feb 2003 12:11:41 -0800
Thank you for this information, Bruce - as well as for your many
contributions to this community.
I am trying to follow this & figure the implications for real world use.
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?
And should this behavior should be the same on Mac & Windoze?
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)
Is Photoshop doing an adaptation based on incorrect data here too?
Another inquiring - sometimes muddled - mind wants to know...
Thanks,
John
on 2/14/03, "Bruce J. Lindbloom" <email@hidden> wrote:
>
The ICC profile that was made by OptiCAL had these exact same RGB
>
chromaticities in its colorant tags. This is *wrong* because the primaries
>
were not adapted from D65 to D50 per ICC specifications. This ICC profile is
>
plain old wrong.
>
>
When this (wrong) profile is loaded into Photoshop's "Color Settings" dialog
>
(as Bob had previously described), Photoshop did what it should, and adapted
>
the primaries from D50 back to the profile's white point (D65). But since
>
the "forward adaptation" had not occurred, this "backward adaptation" yields
>
chromaticities that bear no relationship to reality. This is not Photoshop's
>
fault -- it is a consequence of the broken ICC profile.
>
>
Profiles made with OptiCAL v2.5 and v3.7 both had this same problem.
>
>
If you use OptiCAL to calibrate your monitor to a D50 white, you will not
>
see the problem. The farther away from D50 you go, the worse the problem
>
becomes.
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