Re: monitor profile
Re: monitor profile
- Subject: Re: monitor profile
- From: "tlianza" <email@hidden>
- Date: Wed, 27 Feb 2002 22:53:58 -0500
Hello Henrik,
>
>
By definition the white point must be scaled to D50 in a monitor
>
profile. If a monitor profiling application allowed creation of D65
>
monitor profiles, how would the result would be ICC compliant? Or
>
maybe I didn't follow?
>
You are 100% correct. Tom Beckenham was led astray by one of the most ill
concieved and poorly documented parts of the ICC specification. The White
Point in a monitor profile must always be D50 (The PCS specified white
point). The Red Green and Blue XYZ tags are most definately NOT the XYZ
coordinates of the Red Green and Blue Phosphor. One would expect that the
White point tag and Colorant Tags might actually relate to the White point
and Colorants, but that was not meant to be. The XYZ tags actually are the
matrix which transforms the Colors in the monitor space to the D50 white
point PCS. I have complained about this section of the spec from the day
it was written. The adaptation method was never specified (although the
"Wrong Von Kreis" transform was recommended at one point) so it was
impossible to recover the actual display chromaticities from the profile and
white point from the profile. The next generation specification has a tag to
specifiy the adaptation method that is used. These tags carry an implied
adaptation matrix and the original color temp and chromaticities can be
deduced from the profile.
.
Tom Lianza
Technical Director
Sequel Imaging Inc.
25 Nashua Rd.
Londonderry, NH 03053
email@hidden
_______________________________________________
colorsync-users mailing list | email@hidden
Help/Unsubscribe/Archives:
http://www.lists.apple.com/mailman/listinfo/colorsync-users
Do not post admin requests to the list. They will be ignored.