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2009.04.16 09:42 "wrinting to TIFF_UNDEFINED", by Jachym Cepicky
Hi,
I would like to create custom tiff tag of type TIFF_UNDEFINED. I have
modified libtiff/tif_dirinfo.c, so it contains
{ SOILTEQTIFFTAG_SIGNATURE, -3, -3, TIFF_UNDEFINED,
FIELD_CUSTOM, 0, 1, "Signature" },
in the static const TIFFFieldInfo tiffFieldInfo[] structure.
SOILTEQTIFFTAG_SIGNATURE is macro for 65001.
According to documentation to some kind of proprietary program, the tag
should contain MD5 sum of some file or 0.
When I try to read the data from reference file, which contains the tag,
via tiffinfo, I get following result:
$ tiffinfo DS9204.TIF|grep Signature
Signature:
0x3c,0x7e,0x3c,0xb0,0xb1,0xfb,0x74,0x35,0x3b,0xf0,0x80,0xd1,0x76,0x5b,0x96,0xdb
which is at least something and if I let it print (I'm more familiar
with python than with C)
>>> print 16*"%x" %\
>>> (0x3c,0x7e,0x3c,0xb0,0xb1,0xfb,0x74,0x35,0x3b,0xf0,0x80,0xd1,0x76,0x5b,0x96,0xdb)
I get
3c7e3cb0b1fb74353bf080d1765b96db
which looks like md5sum
I guess, some modifications in tif_print.c have to be done. But this is not the problem.
The problem is, how to set the Signature tag on a new fresh created
file. No matter, if I try
tiffset -s Signature 0
tiffset -s Signature 0x00
tiffset -s 65001 0
tiffset -s 65001 0x00
when I call tiffinfo afterwards, I get no response on this tag.
I tried to set other tags with TIFF_UNDEFINED type, which I found in
tif_dirinfo.c, but none seems to be working.
How to define writeable TIFF_UNDEFINED the correct way?
Thanks
Jachym
--
Jachym Cepicky
e-mail: jachym.cepicky gmail com
URL: http://les-ejk.cz
GPG: http://www.les-ejk.cz/pgp/JachymCepicky.pgp
Key fingerprint: 0C6D 0EAE 76BD 506C F299 ED8A C8AB 74B8 08D4 E08F