TIFF CHANGE INFORMATION

Current Version: v3.5.3
Previous Version: v3.5.2
Master FTP Site: ftp.onshore.com, directory pub/libtiff
Master HTTP Site: http://www.remotesensing.org/libtiff

This document describes the changes made to the software between the previous and current versions (see above). If you don't find something listed here, then it was not done in this timeframe, or it was not considered important enough to be mentioned. The following information is located here:

- Changes in the software configuration
- Changes in libtiff
- Changes in the tools

The ChangeLog will follow, but please note the most important change: LZW compression has been removed.

Unisys has the patent on LZW compression and have been very active in their enforcement of late, demanding payments of $5000 or more from websites using unlicensed software to create GIF's. They could well do the same do persons using libtiff to create LZW compressed TIFF images.

From Burn All GIF's Day:
The catch is that it appears to be difficult or impossible to get a Unisys license to use LZW in free software that complies with the Open Source Definition

Unfortunatly, the removal of LZW compression means that saved image size has grown dramatically. Without a change in the TIFF spec to support another lossless compression format, this is unavoidable.

The library can use zip for lossless compression, but as this is not part of the spec, TIFFs using zip compression may not work with other software

We will be making a patch available that will contain the LZW compression code for users who have either obtained a license from Unisys or are willing to risk it.

LZW decompression is unchanged.

CHANGES IN THE SOFTWARE CONFIGURATION:

- Added zip creation to release makefile target

CHANGES IN LIBTIFF:

- Added html for TIFFWriteTile.3t man page.
- Added some changes to tif_write.c to support rewriting existing fixed sized tiles and strips. Code mods disabled by default, only enabled if REWRITE_HACK is defined for now.
- Added TIFFWriteTile.3t man page.
- Added notes on use of makefile.vc in build.html, and fixed email subscription address.
- Fixed apocalypse-inducing y2k bug in contrib/ras/ras2tiff.c
- Did some casts cleaning up to reduce compiler warnings in tif_fax3.c, from Bruce Carmeron -- modifications of changes made by Frank (sun cc still complained on cast).
- fixed various VC++ warnings as suggested by Gilles Vollant .
- Modified TIFFquery.3t man pages info on TIFFIsByteSwapped() to not imply applications are responsible for image data swapping.
- HTML-ized the man pages, added to html/man
- Removed LZW Compression to comply with Unisys patent extortion.
- Corrected one remaining 16 -> 32 bit value in tif_fax3.c, From Ivo Penzar Added patch from Ivo Penzar to have TiffAdvanceDirectory handle memory mapped files.

CHANGES IN THE TOOLS:

- Fixed apocalypse-inducing y2k bug in contrib/ras/ras2tiff.c

TIFF home page.

Last updated $Date$.