EP0444884A2 Expired / Lapsed EP ⏱️ 0.0 years remaining

Method of orthogonal transform coding/decoding

Assignee: Victor Company of Japan Ltd

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Filing: 1991-02-26

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Granted: —

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Expires: 2011-02-26

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Abstract

Abstract There is provided the method of orthogonal transform coding/decoding to quantize/de-quantize transformed coefficients which are divided into a plurality of bands to which respective different numbers of coefficient are allotted. Quantization/de-quantization tables are arranged on the basis of a probability density function of the coefficient values designed on the assumption of a specified number of coefficients so as to correspond to the number of quantization/de-quantization bits. The values in the quantization/de-quantization tables selected according to the number of quantization/de-quantization bits are adaptivety compensated on the basis of an actual number of coefficients on each band to quantize/de-quantize the coefficient values. <IMAGE>

Inventors

👤 Norihiko Fuchigami
👤 Masaya Konishi
👤 Yasuhiro Yamada

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-11-09 10:52

CPC Classifications

G; G06; G06F; G06F17/00; G06F17/10; G06F17/14; H; H04; H04N; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/126; H04N19/60

Claims Analysis

Total Claims: 3

Claim 1

Independent Claim 150 words

A method of orthogonal transform coding to quantize transformed coefficients which are divided into a plurality of bands to which respective different numbers of coefficients are allotted, characterized by comprising the steps of: arranging a plurality of quantization threshold level-tables designed on the basis of a probability density function of coefficient value on the assumption of a pre-set number of coefficients, the quantization threshold level-tables corresponding to pre-pet plural numbers of quantization bits respectively, selecting a table among the quantization threshold level-tables in response to a number of bits which the quantization of coefficients on a band is to be performed, and compensating the quantization levels in the selected table with the square root of a ratio of the number of coefficients on the band to the pre-set number of coefficients, thus to compare the coefficient values and the compensated threshold levels with each other to quantize the coefficient values.

Claim 2

Dependent Claim 42 words

The method according to claim 1, wherein the step of selecting the table is performed on the basis of calculating a signal-to-noise ratio defined by a ratio of the root-mean-square value of the coefficients on the band to a noise-masking threshold level.

Claim 3

Independent Claim 151 words

A method of orthogonal transform decoding to de-quantize quantized values of transformed coefficients which are divided into a plurality of bands to which respective different number of coefficients are allotted, characterized by comprising the steps of: arranging a plurality of de-quantized value-tables designed on the basis of a probability density function of coefficient value on the assumption of a pre-set number of coefficients, the de-quantized value-tables corresponding to pre-set plural numbers of de-quantization bits, and the steps being the same as each other, selecting a table among the de-quantized value-tables in response to a number of bits by which the quantization of coefficients on a band was performed, and compensating the de-quantized values in the selected table with the square root of a ratio of the number of coefficients on the band to the pre-set number of coefficients, the de-quantized values corresponding to the quantized values of coefficients on the band.

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