Appeal No. 1997-2474 Page 15
Application No. 08/125,590
A method of producing in a computer including a
processing unit ... an output signal including a
plurality of digitized signal samples by performing
an Inverse Discrete Cosine Transform of an input
signal including groups of N input coefficients,
each input coefficient classifiable into one of a
plurality of symmetry classes, the method comprising
the steps of:
precomputing for each of N look up tables, a
plurality of table values equal in number to a
number of possible input coefficient amplitude
values times N divided by a number of symmetry
classes ...;
...
summing results segregated by the symmetry
classes into which the input coefficients are
classified, and
performing at least one vector butterfly
operation corresponding to the plurality of symmetry
classes ....
The examiner admits, “McMillan, Jr. et al. ... does not
disclose the symmetry characteristic that the input samples
can be separately transformed for odd and even portions, then
accumulated to produce the output coefficient as claimed.”
(Examiner’s Answer at 4-5.) Accordingly, he relies on Uramoto
to teach “that by the symmetry of elements in the transform
matrix, the odd and even input samples can be separately
transformed and combined to produce the output coefficient,
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