2009.04.29 07:31 "Re: [Tiff] wrinting to TIFF_UNDEFINED", by Jachym Cepicky
Hi,
really no hint about writing tag of type TIFF_UNDEFINED to existing TIFF file? Does anybody use any TIFF_UNDEFINED tag in libtiff, which works and I could be inspired by it?
Thanks
Jachym
On Thu, Apr 16, 2009 at 11:42:47AM +0200, Jachym Cepicky wrote:
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 0x00tiffset -s 65001 0
tiffset -s 65001 0x00when 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?
--
Jachym Cepicky
e-mail: jachym.cepicky gmail com
URL: http://les-ejk.cz
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