Pulse or digital communications – Bandwidth reduction or expansion – Television or motion video signal
Patent
1998-07-30
2000-11-14
Britton, Howard
Pulse or digital communications
Bandwidth reduction or expansion
Television or motion video signal
3488452, 37524025, H04B 166
Patent
active
061480304
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a motion picture coding and decoding apparatus for coding and decoding motion picture or image data represented in digital manner. More specifically, the present invention relates to a motion picture coding and decoding apparatus free of image degradation.
BACKGROUND ART
In image coding, a method of superimposing different motion picture sequences has been studied. In an article entitled "An Image Coding Scheme Using Layered Representation and Multiple Templates" (Technical Report of IEICE, IE94-159, pp. 99-106 (1995)) discloses a method of forming a new sequence by superimposing a motion picture sequence as a background and a motion picture sequence of a component motion picture or image as a foreground (for example, video image of a character or fish cut out by chromakey technique).
An article "Temporal Scalability Based on Image Content", ISO/IEC/JTC1/SC29/WG11 MPEG95/211(1995) discloses a method of forming a new sequence by superimposing a motion picture sequence of component motion images having high frame rate on a motion picture sequence having a low frame rate.
According to this method, referring to FIG. 27, prediction coding is performed at a low frame rate at a lower layer, and prediction coding is performed at a high frame rate only at a selected area (hatched portion) of an upper layer. However, a frame coded in the lower layer is not coded in the upper layer, but decoded image of the lower layer is copied and used as it is. It is assumed that a portion to which a viewer pays attention, such as a figure or a character is selected as the selected area.
FIG. 26 is a block diagram showing a main portion of a conventional motion picture coding and decoding apparatus. Referring to the left side of FIG. 26, in a coding apparatus of the conventional motion picture and encoding apparatus, first and second skipping units 801 and 802 thin out frames of input motion picture data. The input image data thus comes to have lower frame rate and input to upper layer coding unit 803 and lower layer coding unit 804, respectively. It is assumed that the frame rate for the upper layer is not lower than the frame rate of the lower layer.
Input motion picture as a whole is coded in lower layer coding unit 804. Internationally standardized method of motion picture coding such as MPEG or H.261 is used as the coding method. A decoded image of the lower layer is formed in lower layer coding unit 804, which image is utilized for prediction coding and at the same time, input to a superimposing unit 805.
Only the selected area of the input motion picture is coded in upper layer coding unit 803 of FIG. 26. The internationally standardized method of motion picture coding such as MPEG or H.261 is also used here. Only the selected area is coded, however, based on area shape information. A frame which has already been coded in the lower layer is not coded in the upper layer. The area shape information represents shape of the selected area such as a figure portion, and is a binary image assuming the value 1 at the position of the selected area and the value 0 at other positions. Only the selected area of the motion picture is coded in upper layer coding unit 803, and input to superimposing unit 805.
The area shape is coded utilizing 8 directional quantizing code in an area shape coding unit 806. FIG. 25 depicts the 8 directional quantizing code. As can be seen from the figure, the 8 directional quantizing code represents a direction to a next point by a numerical value, which is generally used for representing a digital figure.
At a frame position where a lower layer frame has been coded, superimposing unit 805 outputs a decoded image of the lower layer. At a frame position where the lower layer frame has not been coded, the superimposing unit forms an image by using coded images of preceding and succeeding two coded lower layers of the frame of interest and one upper layer decoded image of the same time point, and outputs the formed image. The image formed here is input to upp
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patent: 5608458 (1997-03-01), Chen et al.
Hanamura, et al, "A Proposal of Hierarchical Video Signal Coding Scheme to MPEGII", vol. 91 No. 477, Feb. 21, 1992, pp. 1-8.
Etoh, et al, "An Image Coding Scheme Using Layered Representation and Multiple Templates", The Institute of Electronics Information and Communication Engineers, pp. 99-106.
Katata, et al, "International Organization for Standardization, ISO/IEC JTC1/SC29/WG11, Coding of Moving Pictures and Associated Audio," Jul. 1995/Tokyo, p. 1-2.
Aono Tomoko
Ito Norio
Katata Hiroyuki
Kusao Hiroshi
Watanabe Shuichi
Britton Howard
Sharp Kabushiki Kaisha
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