2006.11.19 18:02 "[Tiff] tiffinfo large file issue", by Paul Surgeon

2006.11.19 23:54 "Re: [Tiff] tiffinfo large file issue", by Frank Warmerdam

On Sunday 19 November 2006 23:20, Bob Friesenhahn wrote:

The tiffinfo utility primarily reads TIFF directories, which may occur almost anywhere in the file. If the TIFF directory is placed at the end of a file which is over 2GB in size, then a file offet value bigger than 2GB is necessary to retrieve it. Systems which do not support large files often use a signed 32-bit integer value to represent file offsets (off_t type), and this value overflows at the 2GB offset. Some systems (e.g. Linux and Solaris) require special compilation options in order to use larger file offsets (signed 64-bit integer) in programs so that the programs can support large files.

If all the offsets necessary to access the TIFF directories are less than 2GB, then it may be possible to usefully access the file even if the image raster data causes the file to be larger than 2GB.

That could be the problem.

Is there anyway to rewrite the files and make sure the TIFF directories are at the front of the files?


That is in theory possible, but why do you want to do that? Why not just build the tools properly? Perhaps your hope is to produce tiff files more likely to be compatible with other applications? I a 2.8 GB file is likely to fail in one way or another for applications that can't handle large tiff files. Better to keep your files below 2GB in size if wide compatability is your aim. If your aim is dealing with your own use of the file, then just rebuild the tools to use the large file api.

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    | President OSGeo, http://osgeo.org