Re: Adobe-RGB Different primary colors
Re: Adobe-RGB Different primary colors
- Subject: Re: Adobe-RGB Different primary colors
- From: "dpascale" <email@hidden>
- Date: Mon, 27 Aug 2007 16:39:23 -0400
Hello Raimar,
The Colorsync and Chromix values are indeed D50 coordinates obtained with a
Bradford Chromatic Adaptation Transform.
I just checked and made the conversions both ways (from xyz to XYZ, then
from XYZ to XYZ (Bradford), then XYZ to xyz), for D50 to D65, and D65 to
D50, and obtain the values you give (there are minor differences at the
fourth decimal).
You may have switched the collumns and rows of the Bradford matrix.
Danny Pascale
email@hidden
----- Original Message -----
From: "J. Raimar Kuhnen" <email@hidden>
To: <email@hidden>
Sent: Thursday, August 23, 2007 4:02 PM
Subject: Adobe-RGB Different primary colors
Hallo Color users,
After checking some primary color definitions inside diffeent working
spaces
i´ve noticed that the primary colors in the original Adobe-RGB 1998
profile
differs from the Adobe Documentation for Adobe-RGB 1998.
According to the documenation,the primaries are at:
Red x=0.6400, y=0.3300
Green x=0.2100, y=0.7100
Blue x=0.1500, y=0.0600
White x=0.3127, y=0.3290 (the reference white is D65)
but if you inspect the primary colors in the Adobe-RGB 1998 profile (with
the Colorsync utility or Chromix) one can see a discrepancy especially in
the greens:
Red x=0.6484, y=0.3309
Green x=0.2302, y=0.7015
Blue x=0.1559, y=0.0660
The other deviations in the third column after the comma can be more or
less
ignored, but a difference of x=0.02 and y=0.01 for green cannot be
ignored.
I´ve tried to find the reason for that and have calculated the D65 primary
colors down to D50 by using a chromatic adaption (bradford is Adobe´s
preferred one) but there is no change to the values that the documentation
lists for green. Mostly the blues are influenced by chromatic adaptions.
Does anyone knows why there are different primaries?
Best regards
Raimar
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