2004.07.08 23:14 "[Tiff] LZW and libtiff", by Bob Friesenhahn

2004.07.10 19:44 "Re: [Tiff] LZW and libtiff", by Andrey Kiselev

This topic was lightly discussed in the context of GIF on the debian-legal mailing list. See this message and its references and follow-ups:


If there was a consensus, it seems to be that it's okay to consider the LZW patent over since IBM never enforced their patent. One person also states that the patent is actually for a related but different algorithm (LZMW) which, like LZW, is an LZ78 derivative.

And that is true, we have two different algorithms here.

Most of the discussions I've seen about this topic are about GIF. People seem to forget about LZW compression in TIFF.

In fact there are more places where the LZW was used. Every Linux user can find it in the kernel at the linux/drivers/net/bsd_comp.c.

This is important as it is the best non-lossy compression algorithm supported by virtually all TIFF readers. (Deflate is not as widely supported, JPEG is lossy.) But of course everyone here knows that already.

And LZW is faster than Deflate.

If this happens, what is the schedule for the first release that will include it? Will there be a new 3.6 release with it, or will we wait for 3.7.0 for a non-alpha release that includes LZW by default? (I know, that's not really a fair question.)

It is very easy to enable the LZW in any libtiff release using separate lzw-compression-kit. Those packages are maintained simultaneously, there should not be a big problem neither for the binary package maintainer nor for ordibnary user, which compiles the library from sources.

I can't provide any shedule for the final stable release, but there will be at least one beta release before the final. There are many changes in the build environment, so I want to test it as much as possible.


Andrey V. Kiselev
Home phone: +7 812 5274898 ICQ# 26871517