Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1992-07-31
1993-04-06
Harkcom, Gary V.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
395131, 358458, 358460, 340793, G06F 314, H04N 140, G09G 510
Patent
active
052010309
ABSTRACT:
The distance between the intensity value of the base value (that is, the closest quantized intensity value less than the input intensity value) and the input intensity value is adjusted according to a mapping function between the size of the interval between the intensity values of the base value and the base value +1 (i.e., the next larger quantized intensity value) and the range of values in the dither matrix. By adjusting the distance between the base value and the input intensity value, the correct proportion of base values and base values +1 is maintained regardless of the difference in size of the interval and the range of the dither matrix, thereby insuring that the intermediate intensity values between quantized values are accurately simulated. In one embodiment of the present invention, the range of input intensity values is mapped to the full range of quantized intensity values by mapping the minimum and maximum input intensity values respectively to the minimum and maximum quantized intensity values and evenly distributing the remaining input intensity values between the minimum and maximum quantized intensity values. A second mapping function is then generated between the size of the interval and the size of the dither matrix to adjust the distance values and insure the accurate simulation of intermediate intensity values. In the resulting output, the accumulated error is reduced and the error is evenly balanced and distributed such that the image energy, and therefore the image brightness, is conserved.
REFERENCES:
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patent: 4866534 (1989-09-01), Tada
patent: 4920501 (1990-04-01), Sullivan et al.
patent: 4937761 (1990-06-01), Hassett
patent: 4956638 (1990-09-01), Larky et al.
patent: 4958272 (1990-09-01), Wake
patent: 5073966 (1991-12-01), Sato
Bayerl Raymond J.
Harkcom Gary V.
Sun Microsystems Inc.
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