Image analysis – Image compression or coding – Shape – icon – or feature-based compression
Reexamination Certificate
2000-02-03
2003-06-24
Couso, Jose L. (Department: 2621)
Image analysis
Image compression or coding
Shape, icon, or feature-based compression
Reexamination Certificate
active
06584229
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and apparatus for providing macroblock-based object-oriented coding method of image sequence having a stationary background, which is capable of providing a real time coding process of the image sequence at a low-performance system and reducing the size of video information to be transmitted or stored in an effective manner.
DESCRIPTION OF THE PRIOR ART
Since a video telephone system utilizing moving picture generally uses a communication channel having a extremely limited transmission bandwidth, it is unavoidable to compress image signals in order to reduce the size of video information to be transmitted. One of conventional video compression techniques for reducing the size of information is an object-based coding technique, by which an image is divided into a back ground region and a foreground object region and each region is encoded separately. That is, the input image signal is divided into the background region having little motion and changes, and the foreground object region having large motion and changes, wherein the input image signal includes a plurality of video frames and each frame includes a multiplicity of macro-blocks, each macroblock having 16×16 pixels. Each divided region is coded by using a conventional macro block-based image coding technique, such as known discrete cosine transformation and quantization techniques. In addition, shape information representing each divided region is separately coded and transmitted in order to reconstruct the image signal at a receive side.
Therefore, it is very important to efficiently divide the image signal into two regions and to code the shape information of each divided region at the very high compression rate in order to maximize the coding efficiency. A conventional region division technique divides the image signal in a pixel unit by use of temporal change information or spatial change information of the image signal. That is, the video is divided into a plurality of the regions according to estimating the brightness-change in the pixel unit, thereby, each pixel is estimated as a back ground region or an object region. And such a shape information of a pixel-unit is coded by the chain-type around the outline of each region.
Since very complicated processes should be executed in order to divide the video by the pixel unit in the case of using the object-based coding technique utilizing the conventional region division technique, it is difficult to embody such processes in real time. In addition, the conventional arts may reach a limitation to maximize the coding efficiency, because lots of bits are consumed in order to code and transmit the shape information of each region acquired by pixel unit. The coding rate of the shape information could not be lowered below a certain level, even though a total coding rate is lowered. Therefore, there is a problem that the merit of the object-based coding technique is not utilized efficiently in the case of coding at the low bit rate.
SUMMARY OF INVENTION
It is, therefore, an object of the present invention to provide macroblock-based object-oriented coding method of image sequence having a stationary background which can be coded at a low coding bit rate, hereupon it is possible to embody such processes in real time at a low-performance system and to simply code the shape information of each region with the help of dividing a video not by pixel unit but by 16×16 pixels-sized macroblock-unit, and with the help of dividing the video into two regions and coding each region in order to solve the above-mentioned problems.
In order to achieve the mentioned objects, the present invention comprises: the first step, wherein the inputted video is to be divided into an background region and a foreground object region by unit of macroblock; the second step, wherein an appropriate coding technique for each macroblock, which belongs to the determined region, is to be determined; the third step, wherein a shape information of each region is to be coded according to above-determined coding technique; the forth step, wherein the pixel information of each region is to be coded after determining whether a pixel information for each macroblock is to be coded; and the fifth step, wherein the coded bitstream is to be transmitted or stored.
REFERENCES:
patent: 6005980 (1999-12-01), Elfrig et al.
patent: 6307976 (2001-10-01), Chun et al.
patent: 6459732 (2002-10-01), Chen et al.
Ahn Chie Teuk
Lim Young Kwon
Park Sang Gyu
Couso Jose L.
Electronics and Telecommunications Research Institute
Jacobson & Holman PLLC
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