LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
January 1995
Previous Thread
Next Thread
Previous by Thread
Next by Thread
Previous by Date
Next by Date
Contact
The TIFF Mailing List Homepage
This list is run by Frank Warmerdam
Archive maintained by AWare Systems
Thread
1995.01.24 18:29 "Re: Integrating TIFF extension", by Sam Leffler
To: tiff@sgi.sgi.com
Subject: Integrating TIFF extension
Date: Mon, 23 Jan 1995 17:18:47 PST
From: Adam Rybicki <arybicki@netcom.com>
I have been trying to integrate YCbCr TIFF support into my project by
using libtiff and I ran into some inconsistencies between the spec and
libtiff (this may be the fault of my erroneous interpretation of the
spec, in which case I need to be corrected.)
1. According to the spec, BitsPerSample (quoting from memory) is supposed
to be an array sized by the sample count to allow different number
of bits per sample (e.g. R,G,B = 5,6,5 bits respectively.) Libtiff
always treats BitsPerSample as a single quantity. Is libtiff somehow
"normalizing" the BitsPerSample to the greatest element of that array?
The library does not support multi-sampled images where
the bits/sample vary. This is documented several places
such as intro(3T).
2. YCbCr files cannot be read by scanlines, but reading by strips works
as expected. However, in libtiff there is no way to specify which
particular sample to load if PlanarConfiguration is 2. Or is there?
Tile-based YCbCr files should work, but I have no files in that format.
If PlanarConfig is 2 (separate planes) then individual samples
are in different strips/tiles; to get a particular sample you
read the appropriate strip/tile.
3. Has anyone integrated JPEG support by using jpeglib?
It's coming, but is not yet ready for distribution. When it's
ready there will be a posting to this mailing list.
Sam