Re: [Lcms-user] ICC profiles -> primaries

[Kai-Uwe B. <ku...@gm...>]

Hi,

even in danger to repeat this toppic, here comes my own take:

The primaries stored in the rXYZ,gXYZ and bXYZ tags are part of the
RGB<->XYZ conversion matrix. They are related to D50. 
The whitepoint in wtpt represents the original whitepoint of the media. 

To convert from D50 primaries to oroginal wtpt primaries the chad tag was 
introduced. It holdes the conversion matrix to come from D50 primaries to 
wtpt primaries.

Additional the chromaticity (chrm) tag, natively being in wtpt, can be 
used to hold the origin in the profile.

Without knowing the chromaticities (chrm) or the transform (chad)
conversion is guessing of the right transform. Bradford is a good 
candidate.

The good news, now I understand it, the chrm tag is included by lcms 
during RGB matrix profile generation. Thanks!

regards
Kai-Uwe Behrmann
                                + development for color management 
                                + imaging / panoramas
                                + email: ku...@gm...
                                + http://www.behrmann.name


Am 03.10.05, 12:38 +0200 schrieb Kai-Uwe Behrmann:

> Hi,
> 
> is there a example to get the real xy primaries from an given matrix 
> profile, including white point adaption?
> 
> regards
> Kai-Uwe Behrmann
>                                 + development for color management 
>                                 + imaging / panoramas
>                                 + email: ku...@gm...
>                                 + http://www.behrmann.name
>