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May 2004
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2004.05.15 18:52 "Re: tiffset usage, ResolutionUnits", by Frank Warmerdam
Richard Morris wrote: > Hello all, > > 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, -- ---------------------------------------+-------------------------------------- I set the clouds in motion - turn up | Frank Warmerdam, warmerdam@pobox.com light and sound - activate the windows | http://pobox.com/~warmerdam and watch the world go round - Rush | Geospatial Programmer for Rent