Re: Ooops - D65 != D65 ???
Re: Ooops - D65 != D65 ???
- Subject: Re: Ooops - D65 != D65 ???
- From: Uli Zappe <email@hidden>
- Date: Wed, 20 Jun 2007 08:03:00 +0200
Am 19.06.2007 um 19:07 schrieb Steve Upton:
At 3:03 PM +0200 6/19/07, Uli Zappe wrote:
I just wrote:
Well, at least in this thread nobody said you should always use
D50; the point that you probably refer to is a technical one:
version 4 of the ICC specification says that in ICC profiles,
*internally* values should be stored relative to a D50 white point
This only refers to ICC *monitor* profiles, of course ...
actually all profiles should have white points that are D50 relative.
The v4 spec mentions monitor profiles separately (which is why I
wrote that addition), but you are right, in the end it's all about
D50 (page 33):
9.2.25 mediaWhitePointTag
Tag signature: ‘wtpt’ (77747074h)
Allowed tag type: XYZType
This tag, which is used for generating ICC-absolute colorimetric
intent, specifies the XYZ tristimulus values of
the media white point. If the media is measured under an illumination
source which has a chromaticity other
than D50, the measured values must be adjusted to D50 using the
chromaticAdaptationTag matrix before
recording in the tag. For reflecting and transmitting media, the tag
values are specified relative to the perfect
diffuser (which is normalized to a Y value of 1,0) for illuminant
D50. For displays, the values specified must be
those of D50 normalized such that Y = 1,0 (i.e. 0,9642 1,0 0,8249).
Bye
Uli
________________________________________________________
Uli Zappe, Solmsstraße 5, D-65189 Wiesbaden, Germany
http://www.ritual.org
Fon: +49-700-ULIZAPPE
Fax: +49-700-ZAPPEFAX
________________________________________________________
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden