Appeal No. 1998-1902
Application No. 08/435,592
BACKGROUND
The disclosed invention is directed to a method for diffusing quantization error that
is inherent in converting a continuous tone (gray scale) scan to binary values. The binary
values represent what is to be printed by a printer as black dots, and what is not to be
printed (i.e., leaving white space). The printer cannot print shades of gray, so the error
diffusion filter enables simulation of the scanned continuous image using the binary printed
output. Claim 1 is reproduced below.
1. An error diffusion method for halftoning a digital image formed of an array of
scan lines of pixels, each pixel having a gray value, for forming an output image
including:
scanning each line of image pixels in a processing direction from one end of
the scan line to the other;
determining the gray value of each image pixel; and
error diffusing each of the image pixels by using an error diffusion filter
having weights of 8 - 0 - 4 - 4 expressed in clockwise sequence from the origin.
The examiner relies on the following references:
Barton 5,313,287 May 17, 1994
Eschbach et al. (Eschbach) 5,317,653 May 31, 1994
Claims 1 and 2 stand rejected under 35 U.S.C. § 103 as being unpatentable over
Barton and “the well known prior art.”
Claims 3-12 stand rejected under 35 U.S.C. § 103 as being unpatentable over
Barton, “the well known prior art,” and Eschbach.
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