LibTiff Mailing List
TIFF and LibTiff Mailing List Archive
May 2004
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
2004.05.16 07:18 "Re: tiffset usage, ResolutionUnits", by Andrey Kiselev
On Sat, May 15, 2004 at 02:00:14PM -0400, Richard Morris wrote:
> Can anyone point me to any documentation on usage of the "tiffset"
> utility? I am trying to convert ResolutionUnits on Tiff files from cm
> to inches, and am not successful so far.
tiffset is not a complete ready to use application yet. Fortunately it
is pretty simple to achieve your goal using the following code:
#include <stdio.h>
#include "tiffio.h"
int main(int argc, char* argv[])
{
TIFF *tiff;
double xres = 0.0, yres = 0.0;
if (argc < 2)
return 1;
tiff = TIFFOpen(argv[argc-1], "r+");
if (tiff == NULL)
return 2;
/* For list of available tags and tag values see tiff.h */
if (TIFFSetField(tiff, TIFFTAG_RESOLUTIONUNIT, RESUNIT_CENTIMETER) != 1)
fprintf( stderr, "Failed to set ResolutionUnit.\n");
/* Don't forget to calculate and set new resolution values */
if (TIFFSetField(tiff, TIFFTAG_XRESOLUTION, xres) != 1)
fprintf( stderr, "Failed to set XResolution.\n");
if (TIFFSetField(tiff, TIFFTAG_YRESOLUTION, yres) != 1)
fprintf( stderr, "Failed to set YResolution.\n");
TIFFRewriteDirectory(tiff);
TIFFClose(tiff);
}
But be warned that the new TIFF directory will be added to the file each
time running that program, increasing the file size.
> I see from the libtiff manual that the tag value for ResolutionUnits
> is 296, but I don't know how to set the value. From tiffdump output, I
> saw that tiff files with resolution in cm output "ResolutionUnit (296)
> SHORT (3) 1<3>", while tiffs with resolution in inches output
> "ResolutionUnit (296) SHORT (3) 1<2>".
That is right, inches coded by the value 2, centimeters by the value 3.
Andrey
--
Andrey V. Kiselev
Home phone: +7 812 5274898 ICQ# 26871517