RE: Silly question department, Display Media White Point
RE: Silly question department, Display Media White Point
- Subject: RE: Silly question department, Display Media White Point
- From: Roger Breton <email@hidden>
- Date: Thu, 19 Feb 2015 18:19:18 -0500
Lars,
When I point my instrument to my emissive display and I get a certain set of "absolute" XYZ values like :
X 31.56
Y 33.24
Z 35.54
where Y is the measured Luminance, I guess I must mean "CIE Absolute"?
/ Roger
-----Original Message-----
From: Lars Borg [mailto:email@hidden]
Sent: 19 février 2015 17:43
To: Roger Breton; 'ColorSync'
Subject: Re: Silly question department, Display Media White Point
Do you mean ICC-absolute or CIE absolute?
Lars
-----Original Message-----
From: Roger Breton <email@hidden>
Date: Thursday, February 19, 2015 12:38 PM
To: 'ColorSync' <email@hidden>
Subject: RE: Silly question department, Display Media White Point
>Graeme,
>
>Thank you for fielding my question. I suspected it had something to do
>with the way the specs had changed between v2 and v4 as you many times
>pointed out in the past, here and elsewhere in other forums.
>
>Is recovering the absolute colorimetry through the chad tag very
>complicated?
>I'm on page 93, 94, 95 of the current specs.
>There's a fair amount of "Adopted White" language I had not seen before...
>
>Thank's for the leg up!
>
>Best / Roger
>
>
>-----Original Message-----
>From: colorsync-users-bounces+graxx=email@hidden
>[mailto:colorsync-users-bounces+graxx=email@hidden] On
>Behalf Of Graeme Gill
>Sent: 19 février 2015 16:44
>To: ColorSync
>Subject: Re: Silly question department, Display Media White Point
>
>Roger Breton wrote:
>
>> You see, in both Input and Output profiles, the Tag is encoded with
>> the actual device XYZ colorimetry but not in the case of a Display
>> profile. Was there a time where this wasn't so? I have three recently
>> created monitor profile that all read normalized D50 XYZ under the
>> MediaWhitePoint Tag,
>> 0.96420 1.0000 0.82520.
>
>Hi Roger,
> some ICC V2 profiles will have what you want. Some V2 profiles and all
>V4 profiles will not. For reasons that have not really been explained
>(and in my view, can't be explained in a rational fashion),
>V4 display profiles have been declared to have a D50 media color, even
>thought this is rarely the case.
>The actual media color will be implicit in the 'chad' tag, although I
>doubt any standard CMM' do anything with that tag.
>Such profiles effectively have no absolute colorimetric intent support.
>
>Note that on the other hand, ArgyllCMS V2 display profiles are
>consistent with the standard sRGB and AdobeRGB display profiles, having
>a white point tag that represents the actual media color, therefor
>supporting absolute colorimetric intent.
>
>Graeme Gill.
>
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