2007.01.31 16:39 "[Tiff] 16bit grayscale with colormap", by Reinhard Mayr
aka Czerwinski
Thread
2007.01.31 16:56 "Re: [Tiff] 16bit grayscale with colormap", by Toby Thain
On 31-Jan-07, at 2:39 PM, Reinhard Mayr aka Czerwinski wrote:
I deal with 16bit grayscale TIFFs. The files originate from a 12bit CCD, so the linear conversion 16bit->8bit turns my image almost black.
Maybe I'm missing something, but why don't you just multiply by 16 before storing in TIFF?
--Toby
To cope with that, I would like to add a ColorMap into the TIFF. For testing, I altered an existing 16bit file:
- photometrics = 3 (ColorMap)
- added a colormap (tag 0140), length: 3*2^16= 196608 bytes
Porgrams either refuse this file (ImageMagick viewer) or ignore the colormap and treat as if without (ImageJ).
Is this a proper interpretation of the TIFF specs (TIFF6 specs p.23 allow only 4/8 bits per sample -- why?)? How can I work with the data in terms of leaving original values untouched and just change a LUT/ColorMap/whatever?
Thanks for all advices, hints & pointers!
Cz.
> _______________________________________________
> Tiff mailing list: Tiff@lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/tiff
> http://www.remotesensing.org/libtiff/