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January 2004

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2004.01.15 17:16 "How to determine number of colors in the colormap", by Bill Cassanova
2004.01.15 18:44 "Re: How to determine number of colors in the colormap", by Joris Van Damme
2004.01.15 18:59 "Re: How to determine number of colors in the colormap", by Bill Cassanova
2004.01.15 19:50 "Re: How to determine number of colors in the colormap", by Joris Van Damme
2004.01.15 20:14 "Re: How to determine number of colors in the colormap", by Bill Cassanova
2004.01.15 21:32 "Re: How to determine number of colors in the colormap", by Joris Van Damme

2004.01.15 19:50 "Re: How to determine number of colors in the colormap", by Joris Van Damme

> Thanks for writing.

No problem.

> So to read the colormap am I doing it correctly?  For some reason the
> results I am getting are
> non-sensible.  I would have expected to see values in the range of 0 to
> 255.

It's been a while since I build my interface to that stuff. I plan to return
to it, that's the reason I'm here again, but when it comes to LibTiff,
someone else's advice is no doubt better than my vague memory.

No, you should expect values like the ones you're seeing. The palette
entries is 16bits per channel.

You could check your findings by comparing them with the output of my free
TIFF Tag Viewer application for windows.

http://www.awaresystems.be/free_downloads/astifftools.html

If you want to convert them to the more familiar 8bit per channel range, see
a very recent (and ongoing?) other thread on this subject tittled 'Colormap
and byte padding'. No disrespect to other posters in that thread (especially
no disrespect to myself, grin), but if you want a quick answer without
browsing through the whole thread I should suggest that Marti Maria is the
author of Little CMS and could be considered the authority on the matter.



Joris Van Damme
info@awaresystems.be
http://www.awaresystems.be