Appeal No. 1998-1895 Page 12
Application No. 08/425,990
the performance of "[a]n inverse wavelet transform ... to
obtain the original image" (id. at 2-3), the inverse transform
is not performed on a pair of high-frequency images that were
synthesized by filtering a pair of edge images with an edge
synthesis filter. To the contrary, the AAPA's inverse wavelet
transform is performed on inter alia high-frequency data
resulting from a wavelet transform. The specific admission
follows.
Another prior-art wavelet encoding scheme
employs a basic wavelet that is the first derivative
of a smoothing filter (that is, the first derivative
of a low-pass filtering function). This type of
wavelet acts as a highpass filter. High-frequency
information is obtained by detecting local peaks
(local maxima of absolute values) in the result of
the wavelet transform, which correspond to edges in
the original image. The size and location of the
peak values at a selected scale are encoded, along
with a low-frequency image obtained by smoothing at
the largest scale of the wavelet transform. Fairly
high compression ratios can be obtained in this way.
To reconstruct the original image from the
encoded data, this prior-art method employs an
algorithm derived from a mathematical procedure
involving iterated projections in Hilbert space.
Under ideal conditions, the projections converge
toward a unique set of data that (i) have the
required local peak values and (ii) are within the
range of the wavelet transform operator. An inverse
wavelet transform is then carried out on the
converged data to obtain the original image.
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