Re: [HACKERS] LZ compressing data type

At 23:28 17/11/99 -0500, Tom Lane wrote:
>Philip Warner <pjw@rhyme.com.au> writes:
>> FWIW, I think Unisys patented the LZW algorithm only.
>
>More specifically, Unisys patented Terry Welch's variant of the LZ78
>class of algorithms.  

Hence the 'W' in LZW, no?

>Jan's code falls in the substantially different
>LZ77 class.  There could be problematic patents out there, but Unisys'
>is certainly not one.
>

Is this a legal opinion, or a personal one?


>(If you don't know the difference between LZ77 and LZ78, see the
>comp.compression FAQ ... but don't raise alarms about compression
>patents if you don't know even that much about the field, eh?)

1. I did not raise the alarm, I just responded to it.

2. Since Unisys have moved to block code that does not even use LZW
compression, but happens to be compatible with most GIF decompressors, I
think your comment is misinformed, eh? (See the GD graphics library)

The fear is not whether one wins court cases, but whether you can afford to
fight them.


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