Image analysis – Image compression or coding – Predictive coding
Patent
1995-02-08
1998-11-03
Chang, Jon
Image analysis
Image compression or coding
Predictive coding
382233, 348409, 348445, G06T 900
Patent
active
058321241
DESCRIPTION:
BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATION
This is a national stage application filed under 35 U.S.C. .sctn. 371 of PCT/JP94/00499 filed Mar. 28, 1994.
Picture Signal Coding Method and Picture Signal Coding Apparatus, and Picture Signal Decoding Method and Picture Signal Decoding Apparatus
1. Technical Field
This invention relates to a picture signal coding method and a picture signal coding apparatus, and a picture signal decoding method and a picture signal decoding apparatus suitable when used in the case of recording a moving picture signal onto a recording medium, e.g., a magneto-optical disc or a magnetic tape, etc. to reproduce the recorded moving picture signal to display it on a display, etc., or in the case of transmitting a moving picture signal from the transmitting side to the receiving side through a transmission path to receive it on the receiving side to display it, etc. in television conference systems, television telephone systems, or broadcasting equipments, etc.
2. Background Art
A coding method and a decoding method in which coding in a hierarchical form (hereinafter simply referred to as hierarchical coding) is not applied will be first described, and a coding procedure in the case where hierarchical coding is carried out will be then described.
For example, in systems for transmitting a moving picture signal to remote place, e.g., in television conference system, or television telephone system, etc., a picture signal is coded in a compressed manner by making use of the line correlation or interframe correlation between video signals for the purpose of efficiently utilizing transmission path.
In the case of utilizing the line correlation, a picture signal can be compressed by allowing it to undergo, e.g., DCT (Discrete Cosine Transform) processing, etc.
Moreover, when the interframe correlation is utilized, a picture signal can be coded in a further compressed manner. For example, when frame pictures PC1, PC2, PC3 are assumed to respectively take place at times t=t1, t2, t3 as indicated by A of FIG. 22, a difference between picture signals of frame pictures PC1 and PC2 is calculated to generate picture PC12 as indicated by B of FIG. 22. Moreover, a difference between frame pictures PC2 and PC3 of A of FIG. 22 is calculated to generate picture PC23 of B of FIG. 22. Since pictures of frames adjacent in point of time ordinarily have not so great change, when a difference therebetween is calculated, its difference signal takes a small value. Namely, in picture PC12 designated at B of FIG. 22, a signal of the portion indicated by slanting lines in the figure of picture PC12 of B of FIG. 22 is obtained as a difference between picture signals of frame pictures PC1 and PC2 of A of FIG. 22. In addition, in picture PC23 designated at B of FIG. 22, a signal of the portion indicated by slanting lines in the figure of picture PC23 of B of FIG. 22 is obtained as a difference between picture signals of frame pictures PC2 and PC3 of A of FIG. 22. In view of this, if this difference signal is coded, a quantity of codes can be compressed.
However, even if only the difference signal is transmitted, it is unable to restore original picture. In view of this, pictures of respective frames are caused to be any one of three kinds of pictures of I picture (Intra-coded picture), P picture (Predictive-coded picture) and B picture (Bidirectionally-coded picture), thus to encode a picture signal in a compressed manner.
Namely, as indicated by A and B of FIG. 23, for example, picture signals of frames F1 to F17 are caused to be one unit of processing as group of pictures. Picture signal of the leading frame F1 is coded as I picture. The second frame F2 is processed as B picture, and the third frame F3 is processed as P picture. Then, frames F4 to F17 of the fourth frame and frames subsequent thereto are alternately processed as B picture or P picture.
As a picture signal of I picture, picture signal of that one frame is transmitted as it is. On the contrary, as a picture signal of P picture, fundamentarily, as indica
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Sato Tomoyuki
Tahara Katsumi
Chang Jon
Frommer William S.
Sony Corporation
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