ENCODING METHOD IN COMPRESSION OF GRADATION PICTURE DATA

Japanese Patent JPH01237774

A

PURPOSE:To improve the encoding efficiency of compressing gradation picture data by separately using a prescribed two-encoding system for the unit of blocks. CONSTITUTION:The gradation picture data for the unit of blocks are orthogonally transformed by a two-dimensional discrete cosine transformation device 3 and go to be a transformation coefficient equivalent to one block. Then, the data are uniformly quantized by a first quantizing device 4 and the coefficient number and polarity number of a fixed length code are obtained. These pair numbers are stored in a block buffer memory 6 and a ranking device 5 distributes the block from the coefficient number into plural ranks. In a second quantizing device 7, quantization is executed by a quantizing width, which is determined based on a rank number and setting compression factor, and the cut rate of a high frequency component. Then, in an encoding device 8, the two systems of encoding are executed. Then, one system of the encoding uses both a Huffman code and run-length code and the other system of the encoding uses the Huffman code. In the block of the small quantizing width, or, in the block of a large high frequency cut degree, only the Huffman encoding is used. Then, a code length is shortened and the encoding efficiency is improved.

JPH0281567	DECODER
JP4218446	Electronic camera
JP4701448	Region of interest coding method

YONEKAWA HISASHI
TAKEUCHI HIROSHI

JP6313088A

September 22, 1989

March 18, 1988

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KONISHIROKU PHOTO IND

H04N1/41; G06T1/20; G06T9/00; H04N1/413; H04N19/12; H04N19/126; H04N19/132; H04N19/134; H04N19/146; H04N19/189; H04N19/196; H04N19/423; H04N19/46; H04N19/60; H04N19/625; H04N19/70; H04N19/91; H04N19/93; (IPC1-7): G06F15/66; H04N1/41; H04N1/413; H04N7/133

Hiroo Suzuki

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