US 5,479,211 A · Image-signal decoding apparatus

Abstract

An image-signal decoding apparatus decodes moving-picture data compressed by orthogonal transform, quantization, and variable-length coding for each block. A variable-length code decoding circuit decodes the compressed moving-picture data and outputs the decoded moving-picture data, a moving vector for each block, and block-type information. A distortion eliminator circuit eliminates block distortions from the moving-picture data decoded by the variable-length code decoding circuit. A judging circuit obtains a signal band for each block from the decoded moving-picture data and, based on the band and at least one of the moving vector for each block and the block-type information, changes the distortion elimination characteristics of the distortion eliminator circuit.

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Claims5

Dependent claims

An image signal decoding apparatus for decoding moving-picture data compressed per block by orthogonal transform, quantization and variable-length coding for each block, said apparatus comprising:

variable-length code decoding means for decoding the compressed moving-picture data, and for outputting the decoded moving-picture data, a moving vector per block, and information on block type;
distortion-eliminating means for eliminating a block distortion for moving-picture data decoded by said variable-length code decoding means, according to a distortion elimination characteristic of said distortion-eliminating means;
judging means for obtaining a signal band for each block from the decoded moving-picture data, and for changing the distortion elimination characteristic of said distortion-eliminating means for each block on the basis of at least one of the signal band, the moving vector for each block and the information on block type;
said judging means comprising:
threshold-comparing means for comparing the decoded moving-picture data from said variable-length code decoding means with a predetermined threshold value, and for outputting a comparison result of the comparison between the decoded moving-picture data and the threshold value;
maximum frequency-judging means for computing a maximum frequency in at least one of a horizontal and a vertical direction from the comparison result;
and
filter-determining means for determining at least one of kernel sizes and coefficients of at least one of horizontal and vertical filters on the basis of at least one of the maximum frequency in the horizontal and/or vertical directions, the moving vector and the information on block type.

5 more elements

An image signal decoding apparatus for decoding moving-picture data compressed per block by orthogonal transform, quantization and variable-length coding, said image signal decoding apparatus comprising:

variable-length code decoding means for decoding the compressed moving-picture data, and for outputting the decoded moving-picture data, a moving vector for each block, and information on block type;
inverse quantizating means for performing an inverse quantization for the moving-picture data decoded by said variable-length code decoding means;
inverse orthogonal transforming means for performing orthogonal transform for the moving-picture data to which the inverse quantization has been performed by said inverse quantizating means;
distortion-eliminating means for eliminating block distortions of the moving-picture data output from said inverse quantizating means, according to a distortion elimination characteristic of said distortion-eliminating means;
judging means for obtaining a signal band for each block of the moving-picture data to which the inverse quantization has been performed, and for changing the distortion elimination characteristic of said distortion-eliminating means for each block on the basis of at least one of the signal band, the moving vector for each block output from said variable-length code decoding means and the information on block type;
and
motion compensation predicting means for outputting a motion compensation predictive signal for a subsequent frame of the moving-picture data on the basis of at least one of the moving-picture data when block distortions have been eliminated by said distortion eliminating means, the motion vector for each block output from said variable-length code decoding means and the information on block type.

4 more elements

Dependencies are inferred from the claim text.

Description6,416 words

Summary1,549 words

#1. Field of the Invention

#This invention relates to an image-signal decoding apparatus, and more particularly to an image-signal decoding apparatus that decodes an image transmitted or recorded after high-compression coding.

#2. Description of the Related Art

Brief description of the drawings13 figures

#The accompanying drawings, which are incorporated in and constituted a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the preferred embodiments given below, serve to explain the principles of the invention.

#FIG. 1 is a block diagram showing the construction of an image-signal decoding apparatus according to a first embodiment of the present invention;

#FIG. 2 is a block diagram of an example of the judging circuit of FIG. 1;

Detailed description4,567 words

#First, a general idea of this embodiment will be explained.

#Conspicuousness of image distortion generally changes with the spatial frequency that adjacent images have. For example, when block distortion has occurred in a portion of a fine structure where components range up to a high spatial frequency, the block distortion is not conspicuous so much. In contrast, when block distortion takes place in a portion where there are only low spatial frequency components changing relatively gently, the block distortion tends to be conspicuous.

#Since block distortion is ascribed to discontinuities in the boundary between blocks, it contains components ranging up to a very high spatial frequency. Therefore, by eliminating higher spatial frequencies than those that images near the distortion have, the block distortion can be made inconspicuous.

Facts

Application

08/054,844Filed 29 Apr 1993

Priority

JP 4-11059330 Apr 1992

Granted

26 Dec 1995

Term ended

29 Apr 2013

Estimated · how

Pre-1995 term; greater of 17 years from grant or 20 years from filing when eligible. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification5 codes

H04N 19/86
Using pre-processing or post-processing specially adapted for video compression: involving reduction of coding artifacts, e.g. of blockiness
H04N 19/112
Selection of coding mode or of prediction mode: according to a given display mode, e.g. for interlaced or progressive display mode
H04N 19/503
Using predictive coding: involving temporal prediction
H04N 19/61
Using transform coding: in combination with predictive coding

Image-signal decoding apparatus

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Image-signal decoding apparatus

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Life of this patent

Abstract

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Claims5

Description6,416 words

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Classification5 codes

Life of this patent

Description6,416 words