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TIFF and LibTiff Mail List Archive

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1994.09.02 20:17 "Rules about using libtiff to manipulate tiff with LZW compression?", by Shimon Gonen
1994.09.05 07:21 "Re: Rules about using libtiff to manipulate tiff with LZW compression?", by Karsten Spang

1994.09.05 07:21 "Re: Rules about using libtiff to manipulate tiff with LZW compression?", by Karsten Spang

I have read in compression.faq that there are several patents for compression alogorithms such as LZW and run length encoding.

What do you have to do to use programs or files using these compression algorithms?

For instance, does every program that uses libtiff to import or manipulate tiff files have to pay somebody for these patents?

In principle: yes. But I have heard about anybody doing so. You might want to take a look at the LZW section in the TIFF specification.

Are the patents for compressing the data, uncompressing the data or both?

This might be a good point. According to the documentation for `gzip', only LZW compression is patended, not LZW decompression. I can't, however, guarantee that it will hold in a US court. (And I don't care, as I live in a part of the world where patents on algorithms simply aren't possible:-)

Karsten

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