Appeal No. 1998-0671
Application 08/285,328
arising from the difference between the threshold value and the
actual gray level value in the thresholding step of the screening
process disclosed in the Survey article, the APA, and the direct
thresholding in the background of Eschbach '653 in view of the
teaching in Eschbach '653 that it was known to use error diffusion to
preserve gray density caused by thresholding in a screening process.
In addition, because Eschbach '653 and the APA (at p. 2 of the
specification, describing Eschbach '653) disclose that it was known
that throwing away the error during thresholding results in a loss of
image information, one of ordinary skill in the art would have been
motivated to incorporate error diffusion to prevent this loss of
information. Still further, the teaching in the Survey article of
using error diffusion to provide gray scale rendition when there is
coarse gray scale quantization would have suggested to one of
ordinary skill in the art that error diffusion could be used to
distribute the error caused by the coarse quantization of the fixed
threshold comparator in the Survey article, the APA of figure 1, or
the direct thresholding of Eschbach '653. While we have discussed
the rejection with respect to the steps of method claim 1, the same
reasoning applies to the system claim 7, which is the apparatus
counterpart of claim 1.
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