Appeal No. 1997-0401
Application 08/305,262
processing system such that video artifacts (i.e., graininess)
can be reduced (see specification, pages 1 to 2; Brief, page
3). Appellant recognized that conventional dithering
processes which are known to reduce contouring in images
suffer from the use of a fixed dithering matrix, resulting in
undesirable artifacts, or graininess, being reproduced in an
image (see specification, page 2). As indicated by appellant
(specification, pages 2 to 3; Brief, page 3), when the
dithering matrix added to groups of pixels in an image is
changed frame by frame in a sequence of frames of pixels, it
is possible to reproduce a more natural appearing image and to
prevent graininess normally associated with dithering.
Appellant’s dithering method recited in claims 1 to 20 on
appeal provides that different dithering matrices be picked
over time such that the time-averaged dither intensity at any
given pixel location is zero (specification, page 3). Thus,
by using different dither matrices frame by frame sequentially
in time in patterns that average out to a zero dither
intensity for each pixel location, both graininess and
contouring in an image can be eliminated (see specification,
page 6). As further discussed, infra, we find that the
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