[argyllcms] Re: meta data/comments in .cht file, std. conditions of .cht files
- From: Gerhard Fuernkranz <nospam456@xxxxxx>
- To: argyllcms@xxxxxxxxxxxxx
- Date: Tue, 12 Feb 2008 02:01:37 +0100
Guy K. Kloss wrote:
> Hi,
>
> first of all I've been wondering what illuminant and what observer angle
> the .cht files as shipped with ArgyllCMS are using.
.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.
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.
IT8.7/2
ORIGINATOR "Wolf Faust"
DESCRIPTOR "L* a* b* Batch average data (light D50, viewing angle 2)"
MANUFACTURER "Wolf Faust - http://www.coloraid.de";
CREATED "February 26, 2006"
PROD_DATE "2006:01"
SAMPLE_BACKING "white"
SERIAL "DIN A4 R060101"
MATERIAL "Kodak Professional Ultra Endura - Lustreless"
[...]
or
IT8.7/2
ORIGINATOR "Wolf Faust"
DESCRIPTOR "L* a* b* Batch average data (light F7, viewing angle 10)"
MANUFACTURER "Wolf Faust - http://www.coloraid.de";
CREATED "February 26, 2006"
PROD_DATE "2006:01"
SAMPLE_BACKING "white"
SERIAL "DIN A4 R060101"
MATERIAL "Kodak Professional Ultra Endura - Lustreless"
[...]
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.
Regards,
Gerhard
> It's possible that I've
> overread that piece of information in the documentation. But as the Zen of
> Python also states: "Explicit is better than implicit." ...
>
> That also led me to the next: It would be good to explicitly be able to state
> certain conditions for the .cht file. Especiallyl illuminant and observer
> angle, possibly some more meta information, e. g. what batch or version a
> chart was, etc. Profilemaker (I believe) uses meta tags inside the file as
> this:
>
> ILLUMINATION_NAME "D50"
> OBSERVER_ANGLE "2"
>
> Is something like this possible for .cht files as well? Maybe that would make
> a sensible extension to the file format. Alternatively/additionally comments
> could be used in the file. E. g. a line starting with the hash "#" could be
> interpreted as a comment. Using that also version information of the file
> itself e. g. from CVS or Subversion could be managed ...
>
> Just my thoughts. Any ideas from anybody? Graeme?
>
> Guy
>
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