Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1996-09-12
1998-11-10
Moore, David K.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358458, H04N 140
Patent
active
058352376
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a video signal coding method and an apparatus thereof, and a video signal decoding method and an apparatus thereof, and more particularly is applicable to which decompose the video signal into plural components in consideration of visual importance of the video signal and then code and decode it. Further, the present invention relates to an edge detecting method and an apparatus thereof which is suitable for aforesaid decomposition.
BACKGROUND ART
Conventionally, transformation coding is widely used for image compression. The success of these techniques, beside their energy compaction properties resides in the fact that the distortions due to compression appear in an indirect manner in the spatial domain, namely through the frequency domain components. This leads into a more pleasant distortion, in general. However, the frequency domain distortions in areas containing edges for instance, lead into less desirable artifacts, such as ringing. A solution to reduce this drawback is to classify different regions of the image (commonly square blocks), and to apply different quantization strategies, to each distinct class.
The criterion of classification is of great importance. A measure of the activity based on the AC values of the transform coefficients of each region (block) is usually used. Classification based on activity of AC coefficients is rather good to discriminate between smooth regions and other regions with higher frequency contents. But this technique does not work properly to separate regions containing edges and regions having texture-like activities.
Although, in general frequency domain distortions are invisible in textures, they become very much visible in presence of edges, because of the ringing artifacts mainly. A good classification should therefore be able to classify edge regions and texture regions appropriately, in order to apply more efficient coding strategies into each class in a further stage. More sophisticated activity detections, based on AC coefficients values may be thought in order to cope with this situation. This will however increase the complexity of the system quite a bit, if an efficient strategy is to be found.
DISCLOSURE OF THE INVENTION
In view of the foregoing, the present invention is to provide a video signal coding method and an apparatus thereof and a video signal decoding method and an apparatus thereof which can be improve visual picture quality of the restored image with higher compression rate then ever.
To solve the problem, in the present invention, a local luminance component composed of smooth component of an input video signal is coded by utilizing a first coding method; luminance edge component composed of contour component of the input video signal is coded by utilizing a second coding method by chain coding; and a texture component composed of the component other than the local luminance component and the luminance edge component is coded by utilizing a third coding method.
Further, the present invention provides first coding means for generating a first coded signal by coding the local luminance component composed of the smooth component of the input video signal by utilizing the first coding method; second coding means for generating a second coded signal by coding the luminance edge component composed of the contour component of the input video signal by utilizing the second coding method of chain coding; and third coding means for generating a third coded signal by coding the texture component composed of the component other than the local luminance component and the luminance edge component of the input video signal by utilizing the third coding method.
Further, in a video signal decoding method of the present invention for reconstructing the video signal by utilizing the first coded signal generated by coding the local luminance component composed of the smooth component of the input video signal including at least luminance component, the second coded signal generated by coding the luminan
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Brinich Stephen
Frommer William S.
Moore David K.
Sony Corporation
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