[argyllcms] Re: meta data/comments in .cht file, std. conditions of .cht files
- From: "Guy K. Kloss" <G.Kloss@xxxxxxxxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 12 Feb 2008 14:24:48 +1300
On Tue, 12 Feb 2008 2:01:37 pm Gerhard Fuernkranz wrote:
> .cht files are IMO not the right place for storing this information,
> since they just describe the geometrical layout of the patches of the
> target.
But the .cht files contain the "ground truth" about colour in either CIE XYZ
or CIE LAB colour. This can be found in the "EXPECTED" block for all colour
patches. And this colour is only meaningful with respect to the illuminant
and observer. Or did I misunderstand something here? Otherwise it doesn't
really make sense to have the expected colour tuples in the .cht file ...
Or are the colour tuples just hints for detecting the patch locations?
> Instead, this information should be rather present in the reference file
> which accompanies the scanner target, since it describes, which
> illuminant and observer was used for measuring this particular target -
> and in the reference files for my targets from Wolf Faust, this
> information is basically present (although just as part of the
> DESCRIPTOR), e.g.
That would also satisfy my idea of a separation of responsibilities. As said,
I'm just surprised by the presence of the "EXPECTED" block with colour tuples
in the .cht file ...
> In case of spectral readings, illuminant/observer are not relevant,
> since you can can compute XYZ for arbitrary illumininant/observer
> combinations from the spectral readings anyway.
Very true. But the .cht file does not contain spectral readings, but colour
tuples (three components each) for the patches. Therefore it's under defined
for colourimetric purposes.
Anyway, some kind of meta data, even if it is just in comment lines, is
usually needed or at least useful somewhere ...
Guy
--
Guy K. Kloss
Institute of Information and Mathematical Sciences
Te Kura Putaiao o Mohiohio me Pangarau
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