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From: ndr@tazboy.jpl.nasa.gov (Niles Ritter)
Message-Id: <9701311700.AA27080@tazboy.JPL.NASA.GOV>
To: Eric.W.Hansen@Dartmouth.EDU
Subject: Re:  16-bit TIFF?
Cc: tiff@sgi.com
Sender: owner-tiff@relay.engr.SGI.COM
Precedence: bulk

Eric writes,

>I have some 16-bit data from a CCD camera that was stored as a TIFF file.  Only
>today have I learned that standard TIFF is limited to 8 bits.  

The "Baseline" TIFF file is limited to 8 bits, but most TIFF readers 
worth their salt support at least some of the extended TIFF 6.0 features
such as tiling, 16-bit etc. Adobe Photoshop can do this easy.

>Is there a way
>to read my 16-bit TIFF files?  Ideally, I'd like to have a Unix filter that
>could read my .tif files from standard input and write a text array to standard
>output, which I could redirect to a file and subsequently open with MATLAB.

If you use the libtiff libraries you could write a 20-line program that
does something like this (at least for your flavor of TIFF). You will have
to give the filename as an input parameter, though, since TIFF is not
readily streamable as stdin. Assuming the images are not tiled,
just TIFFOpen the file, TIFFGetField the image sizes and then TIFFReadScanline
the data and dump it out. If the CCD camera software folks were really
on the ball, they may even have set the TIFF tag that tells you whether
the 2-byte pixels should be interpreted as signed or unsigned short
integers.

See also my TIFF Web page at http://www-mipl.jpl.nasa.gov/~ndr/tiff/

 Good Luck!

 --Niles.

>
>Thanks,
>Eric Hansen
>Dartmouth College
>eric.hansen@dartmouth.edu
>
