The end of the JPEG patent - sort of
[Posted May 31, 2006 by corbet]
Forgent Networks is a company which would easily qualify as a patent troll
for many observers. This small company picked up a data compression patent
in 1997, and has been busily using that patent to shake down corporations
ever since. Since this patent is said to cover the JPEG image format,
there is a wide list of possible victims to choose from. Those victims
have dropped more that $100 million into Forgent's bank account, and
Forgent currently has litigation outstanding with some 30 companies.
The Public Patent Foundation chose this patent as one which was vulnerable
to a challenge. The Foundation's work bore fruit on May 25, when the
US Patent Office issued a
ruling on the Forgent patent [PDF]. The resulting press release from the
Public Patent Foundation was triumphant:
"The Patent Office has agreed with our conclusion that it would
have never granted Forgent Networks' '672 patent had it been aware
of the prior art that we uncovered and submitted to them," said Dan
Ravicher, PUBPAT's Executive Director.
It is worth noting that Forgent had a
different spin on the ruling:
...the United States Patent and Trademark Office issued its first
office action, a non-final action, confirming a majority of the
claims in United States Patent 4,698,672. The action upholds 27 of
the 46 claims of Forgent's patent. Forgent will vigorously defend
the remaining claims that were not initially upheld in this first
office action.
Anybody wondering if the world is now safe for JPEG users will clearly need
to look beyond the press releases and dig into the patent and the USPTO
ruling directly. The short story is that, while the independent claims of
U.S.
Patent 4,698,672 have been invalidated, many of the more-specific
dependent claims remain standing. Consider, for example, claim 1:
A method for processing digital signals, where the digital signals
have first values, second values and other values, to reduce the
amount of data utilized to represent the digital signals and to
form statistically coded signals such that the more frequently
occurring values of digital signals are represented by shorter code
lengths and the less frequently occurring values of digital signals
are represented by longer code lengths, comprising,
- forming first runlength code values representing the number of
consecutive first values of said digital signals followed by said
second value,
- forming second runlength code values representing the number
of consecutive first values of said digital signals followed by one
of said other values.
What the Public Patent Foundation asserted is that this claim - covering a
fairly basic run-length encoding scheme - had already been claimed by
another patent: #4,541,012
by Andrew Tescher. The Patent Office agreed, and ruled that claim 1
was invalid.
The story does not stop there, however. There are a number of dependent
claims which make claim 1 more specific; these include:
2. The method of claim 1 further including the step of amplitude
encoding said other values.
3. The method of claim 1 further including the step of encoding
said first and second runlength code values with a sign value.
4. The method of claim 1 wherein said first values have amplitude
zero, said second values have absolute amplitude one, and said
other values have absolute amplitudes greater than one whereby
said first and second runlength codes values are formed
representing the number of consecutive zeros.
5. The method of claim 1 wherein said first values have the highest
frequency of occurrence in said digital signals, wherein said
second values have the next highest frequency of occurrence in
said digital signals, and wherein said other values have the
lowest frequency of occurrence in said digital signals.
Claim 3 (adding a sign value) was also rejected, but claims 2, 4, and 5
were upheld by the Patent Office. The same pattern persists through the
remaining claims: the independent claims were rejected, but the
more-specific versions were allowed. That is why Forgent proclaims that
the majority of its claims had been upheld.
So, to a great extent, the Forgent patent survives, having lost only the
most general of its claims. We asked Dan Ravicher of the Public Patent
Foundation whether this ruling was enough to remove the threat against JPEG
users; his response was:
It likely won't be enough to put an absolute end, but this is a
significant blow to the solitary patent that are using against the
JPEG standard. To the extent we've shown their armor to be made
more of tin or paper, than steel or iron, we've provided the public
the benefit of a more transparent view of the legitimacy of their
claims.
Whether the remaining claims in the patent are applicable to the JPEG
standard is a matter for the courts to determine - and, given the
thirty-some outstanding cases, the courts will certainly have the
opportunity to do so.
There is one interesting additional factor which, thanks to the Public
Patent Foundation's work, may just come into play here. Forgent's patent
was originally filed from a company called Compression Labs, Inc. It turns
out that the Tescher patent, which provided the prior art used against
Forgent's patent, was also developed at Compression Labs. In other words,
when Compression Labs filed for the patent now being wielded by Forgent, it
must have known about the existence of the prior art, since it had
patented that prior art itself. But Compression Labs did not disclose that
prior art to the Patent Office. Failure to disclose known prior art is a
violation of the Patent Office rules. It seems likely that defendants in
Forgent's litigation will find a way to let their respective courts know
that the patent at issue was obtained in bad faith.
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