2007.01.31 16:39 "[Tiff] 16bit grayscale with colormap", by Reinhard Mayr aka Czerwinski

2007.02.01 09:56 "Re: [Tiff] 16bit grayscale with colormap", by Reinhard Mayr aka Czerwinski


thank you for your precious hint -- that was the problem. SHORT is 2 bytes, not 1!

I managed to create a 16bit grayscale TIFF with a colormap.

ImageMagick displays the file (although the colors seem to be weired).

ImageJ ignores the colormap.

Microsoft Tools reject the file.

It seems as if this is a border-line interpretation of the specs and, therefore, questionable whether a solution like that would make sense at all. As far as I am concerned, I think of refraining from 16bit+colormap and try to implement like ImageJ does: info about brightness/contrast in a TIFF-Tag (0x0270 ImageDescription, as a text), and doing all the palette stuff for rendering by my own... :-/

Thank you all for your help!


-------- Original-Nachricht --------
Datum: Wed, 31 Jan 2007 14:06:22 -0500
Von: Phillip Crews <pcrews@cerious.com>
An: tiff@lists.maptools.org
Betreff: Re: [Tiff] 16bit grayscale with colormap

Your color map is not the right length. The color map for a 16-bpp image should be 393216 bytes (196608 words).

Hmmm... I go the same message with ImageMagick's imdisplay.exe. Maybe the error message is just a bit too un-exact: the color map is there (according to the dump), maybe it's just about the unexpected length of 192kB instead of 256 byte? The values of the dump represent exactly what I have in the color map (repeated ASCII "0123456789ABCDEF").

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