Ex parte Cheung et al.

Board of Patent Appeals and Interferences

Mar 29, 2001

08435592 (B.P.A.I. Mar. 29, 2001)

The opinion in support of the decision being entered today was not written for publication
in a law journal and is not binding precedent of the Board.
Paper No. 12
UNITED STATES PATENT AND TRADEMARK OFFICE
____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________
Ex parte ALLAN C. CHEUNG, SCOTT M. HEYDINGER, and SHAUN T. LOVE
____________
Appeal No. 1998-1902
Application No. 08/435,592
____________
ON BRIEF
____________
Before THOMAS, FLEMING, and BLANKENSHIP, Administrative Patent Judges.
BLANKENSHIP, Administrative Patent Judge.
DECISION ON APPEAL
This is a decision on appeal under 35 U.S.C. § 134 from the examiner's final
rejection of claims 1-12.
We reverse.
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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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Claims 13-16 have been canceled, and claims 17-20 have been allowed.
We refer to the Final Rejection (Paper No. 6) and the Examiner's Answer (Paper
No. 9) for a statement of the examiner's position and to the Brief (Paper No. 8) and the
Reply Brief (Paper No. 10) for appellants’ position with respect to the claims which stand
rejected.
OPINION
According to the statement of the rejection with regard to claims 1 and 2, Barton is
relied upon as disclosing a method similar to instant claim 1. (See Answer, page 4.)
However, the reference “does not specifically show...a diffusion filter having weights 8 - 0 -
4 - 4 expressed clockwise from the origin.” (Id.)
The examiner submits that the use of a filter which has a weight expressed
as 8 - 0 - 4 - 4, is not critical to the invention and thus, would have been
obvious as a matter of design choice. The prior art shows different
weighting arrangements with respect to the Floyd and Steinberg methods.
One of ordinary skill in the art would have known to substitute one type of
weighted filter in place of another for the purpose of obtaining a desired
error diffusion result.
(Id. at 4-5.)
Appellants’ specification (at page 7) discusses Barton, the reference applied
against claims 1 and 2. Appellants describe Barton’s error diffusion filter as a “3-weight
filter.” As shown in Barton’s Figures 5A and 5B, and described principally at lines 40-52 of
column 7, Barton reduces error diffusion processing time “by nearly 25 percent.” Barton
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improves upon the Floyd and Steinberg filter (Fig. 5A) by changing the rightmost weights
(7/16 and 1/16) to 8/16 and zero (Fig. 5B). Thus, in the terminology of instant claim 1, the
Floyd and Steinberg filter has weights of 7 - 1 - 5 - 3 expressed in clockwise sequence
from the origin (i.e., the black dot which represents the present pixel being scanned).
Barton’s filter may be expressed as having weights of 8 - 0 - 5 - 3 in clockwise sequence
from the origin. Barton also makes reference to error diffusion filters having more terms
than the four contained in the Floyd and Steinberg filter (see column 6, lines 13-19.)
However, we do not find any suggestion in Barton for the filter having weights of “8 -
0 - 4 - 4 expressed in clockwise sequence from the origin,” as required by instant claim 1.
Nor has the examiner presented any convincing rationale that shows the subject matter as
a whole of claim 1 would have been prima facie obvious to the artisan.
We acknowledge that Barton, with reference to Figures 5A and 5B, teaches moving
weight from the 1/16 (lower right) box to the 7/16 (upper right) box, such that the upper right
box contains weight of 8/16, with the lower right box containing weight of zero. In
retrospect, we also see that moving 1/16 of the weight in the 5/16 (lower center) box to the
3/16 (lower left) box of Figure 5B would result in the filter claimed -- 8 - 0 - 4 - 4. However,
absent this impermissible hindsight, we fail to see, based on the evidence before us, how
the artisan would have been led to select the claimed parameters.
Appellants’ specification provides motivation for the departure from the prior art.
As stated in the “Summary of the Invention,” having “one of the weighted error terms twice
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the magnitude of the other weighted error term, the present technique provides certain
computational advantages.” (Specification, page 8, lines 11-13.) “Each of the two weights
for the error terms is a multiple of 2 so that a shift in a binary shift register can be utilized to
obtain each of the weighted terms.” (Id. at lines 14-16.)
As for the former stated advantage, Barton’s reduction of processing time “by
nearly 25 percent” appears to refer to skipping one division operation with respect to each
pixel, since one of the weighted terms becomes zero, or null. Barton does not disclose a
“computational advantage” in having one of the weighted terms twice the magnitude of the
other weighted term.
As for the latter stated advantage, Barton does not disclose details of the circuitry
for performing the filter operations. The filter circuitry would appear to be substantially no
different from that of the prior art, represented in Barton’s Figure 4 simply as the “Error
Filter.” There was thus no recognition in the reference, and no suggestion, that using terms
that are a power of two would result in faster and simpler operations, allowing use of
simple binary shift registers to perform the required division, as shown in appellants’
Figure 1.
The vaguely-referenced “well known prior art” does not allege any particular
knowledge within the understanding of the artisan, and does not serve to lead to any
motivation for arriving at the subject matter of instant claim 1. While we agree that the
artisan would have been expected to seek to improve upon, and likely change, the filter
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disclosed by Barton, the evidence does not support the view that the requirements of
instant claim 1 would have been prima facie obvious to the artisan.
The examiner’s argument that the “8 - 0 - 4 - 4” weighting scheme has not been
shown to be critical is not well taken. We have pointed out one occurrence in the
specification which provides reasons for the claimed weights. In addition, as appellants
point out in the Brief, the instant specification is replete with sections consistent with the
criticality of the particular weighting scheme claimed.
The examiner also alleges, as stated on page 11 of the Answer, that the claimed
weighting scheme is not critical because the numbers “8 - 0 - 4 - 4” are not used in the
specification’s disclosed filter algorithm. However, as appellants point out in the Reply
Brief at pages 2-3, the original disclosure, which included the Abstract and the original
claims, referred to the filter as having “8 - 0 - 4 - 4” weighting. We find it of no significance
that appellants have chosen to use the terms “8 - 0 - 4 - 4” in the claims, rather than, for
example, using fractions as shown in instant Figure 2. We consider the claims to set forth
appellants’ invention in clear terms, in light of the specification, and the examiner has not
submitted any rejection for indefiniteness under 35 U.S.C. § 112, second paragraph.
Expressing the filter parameters in different ways does not mean that the parameters are
not critical to the invention.
The allocation of burdens requires that the USPTO produce the factual basis for its
rejection of an application under 35 U.S.C. § § 102 and 103. In re Piasecki, 745 F.2d
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1468, 1472, 223 USPQ 785, 788 (Fed. Cir. 1984) (citing In re Warner, 379 F.2d 1011,
1016, 154 USPQ 173, 177 (CCPA 1967)). The one who bears the initial burden of
presenting a prima facie case of unpatentability is the examiner. In re Oetiker, 977 F.2d
1443, 1445, 24 USPQ2d 1443, 1444 (Fed. Cir. 1992). We conclude that the evidence
provided in the instant case is insufficient to support the rejection of claims 1 and 2, and
therefore do not sustain the rejection.
With respect to the rejection of claims 3-8, for which Eschbach is added to Barton
and “the well known prior art,” the Eschbach reference fails to provide the basic teachings
that we find to be missing from Barton. As the examiner correctly notes, Figure 3B of
Eschbach discloses a filter weighting arrangement that has three terms and two weights,
as required by instant claim 3. However, claim 3 requires the precise weights of “8 - 0 - 4 -
4,” and Eschbach, as Barton, fails to provide any reasons for leading the artisan to the
claimed weighting scheme. We therefore do not sustain the section 103 rejection of
claims 3-12.
CONCLUSION
The rejection of claims 1-12 is reversed.
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REVERSED
JAMES D. THOMAS )
Administrative Patent Judge )
)
)
)
) BOARD OF PATENT
MICHAEL R. FLEMING ) APPEALS
Administrative Patent Judge ) AND
) INTERFERENCES
)
)
)
HOWARD B. BLANKENSHIP )
Administrative Patent Judge )
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JOHN J MCARDLE JR
LEXMARK INTERNATIONAL INC
INTELLECTUAL PROPERTY LAW
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