Marti,
thanks for the hint.
An other question comes to my mind:
for the absolute intent you need to guess, when chrm or chad are absent?
Or how does you find out the original primaries, which are lost during the
Wtpt->D50 transformation?
regards
Kai-Uwe Behrmann
+ development for color management
+ imaging / panoramas
+ email: [EMAIL PROTECTED]
+ http://www.behrmann.name
Am 10.10.05, 18:54 +0200 schrieb Marti:
>
> Kai-Uwe,
>
> Just take the ICC profile as a black-box. The fact some profiles
> are implemented as matrix-shaper should be irrelevant.
>
> If you understand primaries as the chromaticity of colorants,
> obtaining the primaries should be as easy as using an absolute colorimetric
> transform from the given profile to XYZ space, and then obtaining the XYZ
> value of each colorant. This will work on all colorspaces,
> not only on RGB.
>
> Regards,
> --
> Marti Maria
> The littlecms project.
> www.littlecms.com
>
>
>
>
>
> ----- Original Message ----- From: "Kai-Uwe Behrmann" <[EMAIL PROTECTED]>
> To: "Lcms Liste" <[email protected]>
> Sent: Thursday, October 06, 2005 8:01 PM
> Subject: Re: [Lcms-user] ICC profiles -> primaries
>
>
> > 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: [EMAIL PROTECTED]
> > + 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: [EMAIL PROTECTED]
> > > + http://www.behrmann.name
> > >
> >
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