Are All Patents Fleeting?
The reasoning of the Court of Appeals for the Federal
Circuit in its recent decision in In Re Nuijten and
its subsequent denial of a petition for rehearing en banc has
the potential effect of invalidating thousands of issued
patents that may fall into newly un-legislated exceptions from
patentable subject matter In Re Nuijten, 500 F.3d 1346
(Fed. Cir. 2007), rehearing denied, 515 F.3d 1361 (Fed. Cir.
2008). The Federal Circuit in In Re Nuijten held that
a transitory propagating signal is not patentable subject
matter under 35 U.S.C. § 101.
Nuijten's patent application discloses a technique for
reducing distortion induced by the introduction of
"watermarks" into signals. In the context of signal
processing, watermarking is a technique by which an original
signal is manipulated so as to embed within it additional data.
The additional data is preferably imperceptible to someone who
views or listens to the signal-for instance, a listener who
plays back a watermarked digital audio file would, if the
watermark is sufficiently unobtrusive, not be able to
distinguish between the watermarked and unwatermarked versions.
An analysis of the file by software capable of detecting the
watermark, however, will reveal the mark's contents.
Publishers of sound and video recordings, for example, find
watermarks useful to embed in the media they distribute
information intended to protect that media against unauthorized
copying. For these publishers and others, watermarking
represents a trade-off: the desired additional data is encoded
directly into the signal, but like any change to a signal, the
watermark introduces some level of distortion. Thus, a key goal
of watermarking techniques is to minimize the distortion so
that the resulting diminution in signal quality is as minimal
Nuijten's technique improves existing watermark
technology by further modifying the watermarked signal in a way
that partially compensates for distortion introduced by the
Figure 2 from the Nuijten application, illustrated above,
demonstrates a relatively simple form of digital audio encoding
called "delta modulation." The smooth line in the
upper graph (labeled 'x') represents a very small slice
of the sound wave to be encoded. The lower graph represents a
digital encoding of that signal. It takes on only two values to
illustrate the signal. These are labeled here as '1'
and '-1,' rather than the usual labeling of these
binary values as one and zero. The sound wave is reconstructed
from the digital signal one step at a time, left to right. If
the digital signal has value '1,' then the
reconstructed sound wave's value is increased slightly. If,
on the other hand, the digital signal has value '-1,'
then the sound wave is decreased by the same amount. Therefore,
the recording is represented by the change (or
"delta") over a very small increment of time, either
'1' for an increase or '-1' for a decrease.
Hence, the encoding scheme is known as "delta
modulation." The result is a close but imperfect
approximation of the original sound wave, illustrated on the
upper graph by 'x' with a caret above it. The fidelity
of the reconstructed sound wave to the original will depend in
large part on the "sample rate"-the length of the
time interval represented by each discrete value in the digital
signal. Representing all of the nuances of the original sound
wave in order to produce a rich, clear recording may require
tens or hundreds of thousands of samples per second.
The watermark of Nuijten is imposed on the signal by
altering, if necessary, every hundredth value of the digital
signal. A reader seeking to extract the watermark from the
digital signal would therefore view only every hundredth value,
disregarding the other 99 along the way; by stringing together
all such values, the watermarked data may be discerned. Every
point where a portion of the watermark is found represents a
possibility that the signal may be distorted. If the watermark
value designated for a certain position and the original value
at that same position happen to coincide, there is no need to
modify the original and hence no distortion. About half of the
time, though, those values will not coincide and the digital
signal will be altered. The result is shown below in Figure 3
from the Nuijten application: the digital value at the point
labeled '21' and illustrated by a vertical dashed line
has been changed from '1' in the original to
'-1.' The reconstructed signal is thus decreased where
it should be increased, and the encoded signal departs from the
original in a pronounced manner.
Nuijten's application teaches that the above illustrated
departure may be minimized by making an additional change to
the watermarked digital signal, as shown below in Figure 4:
Here, the value preceding the one that was modified by the
watermark has also been modified: it was '-1' in the
original signal, but is now '1.'...
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