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2009.04.29 07:31 "Re: 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:
> 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
--
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