EP0577350A2
Expired / Lapsed
EP
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A video signal coding and decoding apparatus with an adaptive edge enhancement filter
Assignee: Panasonic Holdings Corp
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Filing: 1993-06-25
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Granted: —
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Expires: 2013-06-25
Abstract
Abstract Discrete cosine transform (DCT) is a popular coding technique for high compression ratio bandwidth reduction of digital video signal. Basically, DCT converts statistically dependent picture elements into independent coefficients. The resultant coefficients are usually energy concentrated in only a few of the coefficients containing the main part of the picture information which can then be quantized and run-length encoded efficiently. However, when this method is applied to a block of pixel which represents an edge boundary of the object in the picture, ringing effect will appear around the edge of the decoded picture. By detecting the decoded block for edge block, an adaptive edge enhancement filter can be applied to reduce such ringing effect, thereby giving a much less distorted edge.
Inventors
- 👤 Siew Tan Chong
- 👤 Sheng Mei Shen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 16:48
CPC Classifications
H; H04; H04N; H04N19/00; H04N19/85; H04N19/86; H04N19/60; H04N19/625; G; G06; G06T; G06T5/00; G06T5/70; H04N19/50; H04N19/503; H04N19/51; H04N19/527; H04N19/61; H04N19/80; G06T2207/00; G06T2207/20; G06T2207/20172; G06T2207/20182
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
131 words
A video signal decoding apparatus for decoding coded bit stream produced by compressing a video signal through discrete cosine transform, quantizing and variable length coding, said apparatus comprising: decoding means for decoding the coded bit stream to obtain reconstructed quantized data; an inverse quantizer for inversc quantizing the reconstructed quantized data to obtain reconstructed discrete cosine transform coefficients; an inverse transformer for inverse transforming the reconstructed discrete cosine transform coefficients to obtain reconstructed blocks of pixel data; an edge detector for detecting an edge block forming an edge of an image from the reconstructed blocks of pixel data, and producing an edge detection signal upon each detection of an edge block; and a smoothing filter means responsive to the edge detection signal for smoothing the pixel data in the edge block.
Claim 2
Dependent Claim
101 words
An apparatus according to claim 1 wherein said smoothing filter comprises: means for performing convolution on a pixel by pixel basis on the edge block with an adaptive averaging filter mask; means for subjecting every neighboring pixel of said pixel to be convoluted with a threshold test to determine if said neighboring pixel belongs to the same side of the picture edge as said pixel to be convoluted; means for including in the averaging process a neighboring pixel belonging to the same side of the edge as said to be convoluted, and excluding the remaining neighboring pixels from the averaging process.
Claim 3
Dependent Claim
173 words
A video signal coding and decoding apparatus comprising: a block former for dividing an input digital video signal into blocks of pixel data; a discrete cosine transformer for subjecting each block of pixel data to discrete cosine transform to obtain discrete cosine transform coefficients; a quantizer for quantizing the discrete cosine transform coefficients to obtain quantized data; encoding means for encoding the quantized data to obtain a coded bit stream; decoding means for decoding the coded bit stream to obtain reconstructed quantized data; an inverse quantizer for inverse quantizing the reconstructed quantized data to obtain reconstructed discrete cosine transform coefficients; an inverse transformer for inverse transforming the reconstructed discrete cosine transform coefficients to obtain reconstructed blocks of pixel data; an edge detector for detecting an edge block forming an edge of an image from the reconstructed blocks of pixel data, and producing an edge detection signal upon each detection of an edge block; and a smoothing filter means responsive to the edge detection signal for smoothing the pixel data in the edge block.
Claim 4
Dependent Claim
102 words
An apparatus according to claim 3, wherein said smoothing filter comprises: means for performing convolution on a pixel by pixel basis on the edge block with an adaptive averaging filter mask; means for subjecting every neighboring pixel of said pixel to be convoluted with a threshold test to determine if said neighboring pixel belongs to the same side of the picture edge as said pixel to be convoluted; means for including in the averaging process a neighboring pixel belonging to the same side of the edge as said pixel to be convoluted, and excluding the remaining neighboring pixels from the averaging process.
References Cited (Backward Citations)
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