Do I have to pay Unisys to use the LZW algorithm?

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Hi, I'm about to write a GIF decoder and I've been reading a number of articles on the format only to find that the Lempel-Ziv-Welch (LZW) compression algorithm employed by GIF files was patented in 1983 by Walsh for Sperry Corp. and is now in the hands of Unisys. I then read that the patents had expired across the world by 2004, so am I safe to use it without have to pay anyone?

Posted 18-Dec-11 0:45am

J. Broun

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Mehdi Gholam · Answer 1 · 2011-12-18T01:38:00

Solution 2

When the patents expired in 2004 you are free to use the LZW compression scheme on it's own or in the GIF format, without licensing payments.

Posted 18-Dec-11 1:38am

Mehdi Gholam

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Amir Mahfoozi 18-Dec-11 12:19pm

+5

Mehdi Gholam 18-Dec-11 14:39pm

Thanks

Richard MacCutchan · Answer 2 · 2011-12-18T01:27:00

Solution 1

Why not ask the patent holder; they are the only people who can honestly answer the question.

Posted 18-Dec-11 1:27am

Richard MacCutchan

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J. Broun 18-Dec-11 9:02am

Okay, I've emailed them, so I'll see what happens then, I expect that Mehdi Gholam was right (below).