Image compression and expansion device

Details Image compression and expansion device Image compression and expansion device

1997-08-28

1999-12-21

Lee, Thomas D.

Image analysis

Image compression or coding

Quantization

358426, 358430, 358539, 382232, 382248, H04N 141, H04N 146

Patent

active

060059826

ABSTRACT:
The image compression device comprises: a DCT processing unit in which original image data is subjected to a two-dimensional discrete cosine transformation to obtain DCT coefficients; and a quantization processing unit in which the DCT coefficients are quantized by a default quantization table to obtain quantized DCT coefficients. In an optimum quantization table generation unit, an optimum quantization table is generated in such a manner that a quantization error between each of the DCT coefficients and each of the corresponding dequantized DCT coefficients, which are obtained by dequantizing each of the quantized DCT coefficients using the optimum quantization table, becomes a minimum value. The quantized DCT coefficients are compressed to obtain compressed image data, which is stored in a recording medium, together with the default quantization table and the optimum quantization table.

REFERENCES:
patent: 5384849 (1995-01-01), Jeong
patent: 5396567 (1995-03-01), Jass
patent: 5410351 (1995-04-01), Kojima
patent: 5412484 (1995-05-01), Yoshikawa
patent: 5497246 (1996-03-01), Abe
patent: 5666209 (1997-09-01), Abe
patent: 5708509 (1998-01-01), Abe
patent: 5850484 (1998-12-01), Beretta et al.

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