Maybe someone can clear this up for me. Comparing
chromaticity coordinates of my CG220 with that of aRGB, I noticed that
calculating the values from XYZ gave me different results than reported by
Photoshop. I simply took XYZ tristimulus values XYZ tags the profile as
reported by the Colorsync utility and plugged them into the x=(X/(X+Y+Z)),
y=(Y/(X+Y+Z)) equation. I confirmed my results with that of the CIE Color
Calculator at Bruce Lindbloom’s site.
So calculating chromaticities of the AdobeRGB profile in
this manner, and comparing these values to those reported by Photoshop for
AdobeRGB, you’ll notice a difference:
Calculated from XYZ
Red: x=0.6484, y=0.3309
Green: x=0.2302, y=0.7015
Blue: x=0.1559, y=0.0660
Photoshop reported
Red: x=0.6400, y=0.3300
Green: x=0.2100, y=0.7100
Blue: x=0.1500, y=0.0600
Its not an earth shaking difference, but it makes me wonder
how the values are calculated. I find the same issue when calculating xy for my
CG220 profile as well. Further, if I select a profile to emulate in Eizo’s
Color Navigator, the x,y values are identical to what I would get in Photoshop.
Does anyone know how Photoshop/ColorNavigator are calculating chromaticity values?
_______________
Michael Eddington
North American Color, Inc.
www.nac-mi.com