Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1991-11-29
1993-08-17
Kostak, Victor R.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358135, H04N 713
Patent
active
052374106
ABSTRACT:
A video signal encoding apparatus of the type in which inter-frame difference values for respective picture elements are subjected to orthogonal transform processing and the resultant transform coefficients are quantized and encoded, with respective values of quantization step size applied to successive 2-dimensional blocks of picture element values being varied such as to control the encoded data bit stream to a constant bit rate, in which the quantization step size for each block is also controlled in accordance with whether or not the block lies on a border between a visually smooth region of the picture expressed by the video signal and a region in which substantial changes occur in the picture. The step size can thereby be set to be sufficiently small, in the case of specific blocks for which is necessary to use a small size of quantization step in order to prevent noise from appearing in the picture obtained from the decoded video signal.
REFERENCES:
patent: 4829376 (1989-05-01), Hammer
patent: 4941043 (1990-07-01), Jass
patent: 5010401 (1991-04-01), Murakami et al.
"Adaptive Coding of Monochrome and Color Images" by Wen-Hsiung Chen et al IEEE Transactions on Communications, vol. COM-25, No. 11, Nov. 1977; pp. 1285-1292.
Rec. H.221, "Frame Structure for a 64 kbit/s Channel in Audiovisual Teleservices" Melbourne, 1988.
Rec. H.261, "Codec for Audiovisual Services at n.times.384 kbit/s" Melbourne, 1988.
Kostak Victor R.
Matsushita Electric - Industrial Co., Ltd.
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