IMAGE CODER, IMAGE ENCODER, AND CODING DECODING SYSTEM

Japanese Patent JP3681835

B2

PROBLEM TO BE SOLVED: To reduce number of samples of color difference components, to decrease color noise, and to improve the coding efficiency by detecting a state change of image data and selecting a format.
SOLUTION: An input image signal is converted into a digital signal by an A/D converter 1 and the format is converted. The image data are converted into image data of other 4:2:0 format by using a local format 2. Since the sample density of the color difference component of this format is low, the total sample number to be coded is reduced and the compression efficiency is enhanced. Then an image state discrimination section 3 selects an output 102 of the local format 2 or original image data 101 and a DCT 4 is used to convert the selected data into a conversion coefficient 104 of a spatial frequency region. Moreover, a quantization section 5 quantizes the coefficient to convert the DCT coefficient into linear information 105 and it is variable-length-coded by a variable length coder 6. The coded data are stored in a buffer 7, from which a coded bit stream is outputted. Thus, color noise is reduced and the coding efficiency is increased.

Kotaro Asai
Takahiro Fukuhara
Atsushi Murakami

JP26966996A

August 10, 2005

October 11, 1996

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Mitsubishi Electric Corporation

H04N11/04; G06T9/00; H04N19/126; H04N19/132; H04N19/134; H04N19/136; H04N19/137; H04N19/139; H04N19/147; H04N19/152; H04N19/176; H04N19/186; H04N19/196; H04N19/423; H04N19/46; H04N19/50; H04N19/503; H04N19/51; H04N19/567; H04N19/59; H04N19/61; H04N19/625; H04N19/70; H04N19/85; H04N19/91; (IPC1-7): H04N11/04; H04N7/32

JP6205438A
JP7221993A

Shoji Mizoi
Keiko Hada
Sanmei Takeuchi
Hiroto Yamachi

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