Appeal No. 1998-3393
Application No. 08/763,326
each less significant bit (LSB) of the M-bit images are
determined based on the threshold for the most significant bit
and the neighboring pixel values. Appellants assert at page 3
of the specification that, by applying the thus determined
thresholds to quantize the N-bit image pixels to produce the M-
bit image, the number of bits in a gray scale document image is
reduced while the contrast of the characters and lines in the
document is enhanced.
Claim 1 is illustrative of the invention and reads as
follows:
1. A method of generating an M-bit grayscale image from an
N-bit grayscale image, where 1<M<N, comprising the steps of:
a) for each pixel in the N-bit image,
i) determining a threshold, based on the values of
neighboring pixels, for generating the most significant bit
(MSB) of the M-bit image,
ii) determining thresholds, based on the threshold
determined in step i) and the values of surrounding pixels, for
each successive less significant bit(s)(LSB) of the M-bit image;
and
b) applying the thresholds to quantize the pixels in the N-
bit image to produce the M-bit image.
The Examiner relies on the following prior art:
Itoh et al. (Itoh) 4,682,869 Jul. 28,
1987
2
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