Facsimile and static presentation processing – Facsimile – Recording apparatus
Patent
1992-10-09
1996-06-04
Ro, Bentsu
Facsimile and static presentation processing
Facsimile
Recording apparatus
395114, 382250, 382280, G06F 1710
Patent
active
055238475
ABSTRACT:
The objects of this invention are accomplished by rearranging the DCT process such that non-trivial multiplications are combined in a single process step. In particular, the DCT equations for the application of the two-dimensional DCT process on k.times.k points are factored into 1) a permutation matrix, 2) a diagonal matrix, and 3) a matrix whose product with an arbitrary vector having k.sup.2 points requires considerably fewer non-trivial multiplications. Furthermore, in some cases none of these non-trivial multiplications are nested; that is, no output of a non-trivial multiplication is ever involved in another multiplication operation. The diagonal matrix is not unique for any set of data. Once the diagonal matrix elements are chosen the remaining factors are developed. When the factorization is complete, the diagonal matrix is absorbed into the quantization step which follows the DCT process. The quantization step is the multiplication of a diagonal matrix by the DCT output data. The quantization diagonal matrix is combined with the diagonal matrix of the DCT to form one multiplication process by which non-trivial elements multiply data. This combination of multiplication steps reduces the number of non-trivial multiplications in the DCT process. In addition, the non-trivial multiplications are approximated by multiplications by rational numbers, whose computation is achieved with additions, subtractions and shift operations (multiplications by powers of 2). This approximation procedure offers greater numerical accuracy than a procedure based upon approximating the multiplication factors of a standard DCT process with rational factors because the number of non-trivial multiplications have been minimized and none are nested. Furthermore, if the quantization constants are chosen so that they are all either powers of 2 or sums and differences of powers of 2, then the quantization process itself can be achieved with either shifts only or with shifts and additions and subtractions only. Finally, the same reduction in non-trivial multiplications is provided for the inverse DCT and dequantization process.
REFERENCES:
patent: 3920974 (1975-11-01), Means
patent: 3971927 (1976-07-01), Speiser et al.
patent: 4152772 (1979-05-01), Speiser et al.
patent: 4196448 (1980-04-01), Whitehouse et al.
patent: 4385363 (1983-05-01), Widergren et al.
patent: 4675836 (1987-06-01), Arnould et al.
patent: 4679163 (1987-07-01), Arnould et al.
patent: 4791598 (1988-12-01), Liou et al.
patent: 4797847 (1989-01-01), Duhamel
patent: 4805017 (1989-02-01), Kaneko et al.
patent: 4829465 (1989-05-01), Knauer et al.
patent: 4841464 (1989-06-01), Guichard et al.
patent: 4974078 (1990-11-01), Tsai
patent: 5001559 (1991-03-01), Gonzales et al.
patent: 5021891 (1991-06-01), Lee
patent: 5029122 (1991-07-01), Uetani
patent: 5212742 (1993-05-01), Normile et al.
patent: 5253078 (1993-10-01), Balkanski et al.
patent: 5321725 (1994-06-01), Paik et al.
patent: 5333212 (1994-07-01), Ligtenberg
Feig Ephraim
Linzer Elliot N.
Harper Blaney
International Business Machines - Corporation
Morris Daniel P.
Ro Bentsu
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