Re: Photoshop 6/7 problems with OptiCAL (or Photocal) profiles
Re: Photoshop 6/7 problems with OptiCAL (or Photocal) profiles
- Subject: Re: Photoshop 6/7 problems with OptiCAL (or Photocal) profiles
- From: "Bruce J. Lindbloom" <email@hidden>
- Date: Mon, 17 Feb 2003 10:27:34 -0600
Ian Lyons wrote:
>
Typically the blue and green chromacity values as reflected by the
>
simplified profile in Photoshop will be significantly different of those
>
from just about every other application I've used. I don't pretend to
>
understand why this should be but to say that:
>
>
"the difference is visually indistinguishable expect in the most highly
>
saturated colors (beyond the general photo range) on the red side of the
>
color space, where it is slightly distinguishable."
>
>
isn't what I see. May be I need new spectacles :-)
Keep your specs, Ian. You're right on the money. I calculated the color
error to see what colors are most affected, and by how much. For the test I
am assuming you have a "perfect" sRGB monitor (i.e. its white point is D65
and it has sRGB primaries) which is to be profiled with OptiCAL. As I have
stated before, there is no error in neutrals, and the errors increase as the
color moves away from the neutral scale. It will be largest at the pure sRGB
primaries. Here are the errors at the sRGB primaries:
R = 8.21 delta E
G = 11.16 delta E
B = 17.43 delta E
That corresponds with Ian's observations. These colors are not "beyond the
general photo range," nor do I think errors of this magnitude would be
"indistinguishable."
BTW, I have heard from ColorVision that this problem is present in all
versions of OptiCAL, on all platforms. I'm sure they will have a fix
released very soon.
--
Bruce J. Lindbloom
email@hidden
http://www.brucelindbloom.com
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