Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1989-07-05
1991-09-10
Peng, John K.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
350141, 350339, 375 25, H04N 712, H04N 704, H04N 595
Patent
active
050478524
ABSTRACT:
An adaptive transform encoder can keep a recording rate of a digital signal at a constant level. It comprises a unit for orthogonal-transforming one block of digital input signal, a unit for calculating an activity index of the orthogonal-transformed block, a unit for comparing the activity index of the block with a predetermined reference, a unit for classifying the block to a standard bit class having a predetermined number of bits when the activity index of the block is equal to the reference, classifying the block to a low bit class having a smaller number of bits than the predetermined number of bits of the standard bit class when the activity index of the block is smaller than the reference, and classifying the block to a high bit class having a larger number of bits than the predetermined number of bits of the standard bit class when the activity index is larger than the reference, a quantization unit for quantizing the input signal of the block with the number of bits designated by the bit class, a unit for selecting the block of the low bit class from the quantized blocks, an allocation unit for adding to the selected block of the low bit class the data having more bits than the number of bits of the standard bit class of the block of the quantized high bit class, and an encoder unit for encoding the quantized block signal.
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patent: 3984626 (1976-10-01), Mounts et al.
patent: 4535472 (1985-08-01), Tomcik
patent: 4757383 (1988-07-01), Tanaka
patent: 4805030 (1989-02-01), Tanaka
"Adaptive Vector Quantization of Picture Signals in Discrete Iosine Transform Domain"; Aizawa et al.; Papers of the Institute of Electronics and Communication Engineers of Japan; Mar. 1986; vol. J69-B, No. 3; pp. 228-236.
"Adaptive Cooling of Monochrome and Color Images"; W. Chen et al.; IEEE Transactions on Communications; vol. COM-25, No. 11; Nov. 1977; pp. 1285-1292.
Doi Nobukazu
Eto Yoshizumi
Hanyu Hiroyuki
Izumita Morishi
Mita Seiichi
Hitachi , Ltd.
Peng John K.
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