Image analysis – Image compression or coding – Predictive coding
Patent
1998-01-28
2000-11-14
Grant, II, Jerome
Image analysis
Image compression or coding
Predictive coding
3582612, 358432, 358433, H04N 1415, H04N 1417, G06K 936
Patent
active
061481092
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an image predictive coding apparatus and method, image predictive decoding apparatus and method and recording medium. The present invention relates, in particular, to an image predictive coding apparatus and method as well as image predictive decoding apparatus and method for storing digital image data of an image which is a static image or a dynamic image into a recording medium such as an optical disk or transmitting the data through a communication line. The present invention also relates to a recording medium in which a program including the steps of the image predictive coding method is recorded as well as a recording medium in which a program including the steps of the image predictive decoding method is recorded.
BACKGROUND ART
For the purpose of efficiently storing or transmitting a digital image, the image is required to be coded in a compression coding manner. As a method for coding a digital image in a compression coding manner, there is a waveform coding method of sub-band coding, wavelet coding, fractal coding or the like other than discrete cosine transform (referred to as a DCT transform hereinafter) represented by JPEG (Joint Photographic Experts Group) and MPEG (Motion Picture Experts Group). For the purpose of removing a redundant signal between images, an inter-image prediction with a motion compensation is executed, thereby subjecting a differential signal to waveform coding.
According to the MPEG system, an input image is processed while being divided into a plurality of 16.times.16 macro blocks. One macro block is further divided into 8.times.8 blocks and quantized after undergoing 8.times.8 DCT transform. This is called an intra-frame coding.
On the other hand, according to a motion detection method inclusive of block matching, a prediction macro block having the minimum error with respect to the objective macro block is detected from other frames adjacent in time, the detected prediction macro block is subtracted from the objective macro block thereby forming a differential macro block, and this macro block is quantized after undergoing 8.times.8 DCT transform. This is called an inter-frame coding, and the prediction macro block is called a prediction signal of the time domain. According to MPEG described above, no image is predicted from an identical frame.
A normal image has spatially similar regions, and an image can be approximated to a spatial region by utilizing this characteristic. In a manner similar to that of the prediction signal of the time region, a prediction signal can also be obtained from an identical frame. This is called a prediction signal of the spatial region.
Since spatially adjacent two pixel values are close to each other, the prediction signal of the spatial region is generally located close to the objective signal. On the other hand, on the receiving side or the reproducing side, a signal which has been coded and reproduced in the past is required to be used for the prediction signal since the original image is absent. From these two factors, the prediction signal of the spatial region is required to be generated at high speed. This is because the signal is used for the generation of a prediction signal immediately after the pixel value is decoded and reproduced.
Therefore, the prediction signal of the spatial region is required to be generated simply with high accuracy. Furthermore, a speedily operable construction is required in a coding apparatus and a decoding apparatus.
The coding of image data has been widely used in many international standards such as JPEG, MPEG1, H.261, MPEG2 and H.263. Each of the latter standards has a more improved coding efficiency. That is, much efforts have been devoted to further reducing the number of bits than in the conventional standards in expressing the same image quality.
Coding of image data of a dynamic image is comprised of intra-frame coding and prediction frame coding. Among these, the intra-frame coding refers to coding inside the screen of one frame. In a re
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Boon Choong Seng
Shen Sheng Mei
Tan Thiow Keng
Grant II Jerome
Matsushita Electric - Industrial Co., Ltd.
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