2004.05.15 18:52 "Re: [Tiff] tiffset usage, ResolutionUnits", by Frank Warmerdam
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. 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>".
So, it seemed to me that "tiffset -s 296 2 test.tif" should change the "ResolutionUnit flag to the value required for inches, but I keep receiving the error _TIFFVSetField: test.tif: Bad value -1077938501 for "ResolutionUnit". What are the possible values for ResolutionUnit, and how do I set them? (I am using Tiff library 3.6.1, on FreeBSD)
Or, if there are any other (shell scriptable) utilities that would do this job, I would appreciate the info.
Richard,
Unfortunately, tiffset only works for string fields, not numeric ones so I don't think there is a handy way to do what you want.
The following are the documented values for resolution units, if you find a way to use them:
#define TIFFTAG_RESOLUTIONUNIT 296 /* units of resolutions */
#define RESUNIT_NONE 1 /* no meaningful units */
#define RESUNIT_INCH 2 /* english */
#define RESUNIT_CENTIMETER 3 /* metric */
Best regards,
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I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com
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