EP0554871A2
Expired / Lapsed
EP
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Method and apparatus for encoding a digital image signal
Assignee: Sony Corp
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Filing: 1993-02-04
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Granted: —
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Expires: 2013-02-04
Abstract
Abstract A digital image signal is encoded for recording by placing in a sync block approximately an integer number of macro blocks representing orthogonally transformed image data for a certain portion of the image. When a sync block is reproduced at high speed, the reproduced data therein corresponds to a displayable portion of the image including DC components and both low and high frequency AC components. Also, each sync block contains fixed length areas for the orthogonal transform coefficient data according to the 4:1:1 (or 4:2:0) format in which four blocks of luminance coefficients and two blocks of color difference coefficients represent a certain portion of an image, and also contains at least one fixed length overflow area for the high frequency coefficients which exceed the capacity of the fixed length coefficient areas. An error in the low frequency coefficients in the fixed length areas does not harm the high frequency coefficients since they are in separately addressed areas. Before a set of macro blocks is compressed into variable length encoded data, with the amount of encoded data for each set being kept within a target value so as to fit into fixed length recording tracks, the macro blocks are shuffled so that the central portions of an image are at the beginning of the set for reducing the noticeability of errors in a reproduced image.
Inventors
- 👤 Masaki C/O Sony Corporation Oguro
- 👤 Yanagihara Naofumi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 20:40
CPC Classifications
H; H04; H04N; H04N21/00; H04N21/20; H04N21/23; H04N21/238; H04N21/2387; H04N9/00; H04N9/79; H04N9/80; H04N9/804; H04N9/8042; H04N9/8047; H04N11/00; H04N11/04; H04N11/042; H04N11/044; H04N19/00; H04N19/10; H04N19/102; H04N19/124; H04N19/134; H04N19/136; H04N19/14; H04N19/146; H04N19/149; H04N19/169; H04N19/17; H04N19/176; H04N19/18; H04N19/60; H04N19/85; H04N19/89; H04N21/236; H04N21/40; H04N21/43; H04N21/434; H04N7/00; H04N7/24; H04N5/00; H04N5/76; H04N5/78; H04N5/782; H04N5/783
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
126 words
A method for encoding a digital image signal, comprising the steps of: orthogonally transforming said digital image signal into transformed macro blocks containing DC and low frequency AC components of said digital image signal, encoding an encoding set comprised of a predetermined number of said transformed macro blocks using a variable length code into an amount of encoded data in accordance with a target amount, and forming said encoded data corresponding to an approximately integer number of transformed macro blocks into a sync block having a fixed length and also having DC component areas and low frequency AC component areas at predetermined positions, with the encoded data representing said DC and low frequency AC components being in said DC and low frequency AC component areas, respectively.
Claim 2
Dependent Claim
35 words
The method of claim 1; further comprising the steps of blocking said digital image signal into image data blocks, and shuffling a spatial sequence of said image data blocks before said step of orthogonally transforming.
Claim 3
Dependent Claim
82 words
The method of claim 2; wherein, a predetermined number of said image data blocks form a respective shuffling set of macro blocks, and, in said step of shuffling, central macro blocks of each said shuffling set which correspond to central portions of an image represented by said digital image signal are shuffled to precede other macro blocks of the respective shuffling set which correspond to other portions of said image that are less centrally located in said image than said central portions.
Claim 4
Dependent Claim
28 words
The method of claim 1; wherein said step of orthogonally transforming includes performing a discrete cosine transformation on said digital image signal to produce said transformed macro blocks.
Claim 5
Dependent Claim
51 words
The method of claim 1; wherein said step of encoding includes estimating a quantizing number for said encoding set based on said target amount, quantizing said macro blocks in said encoding set in accordance with said quantizing number, and variable length coding the quantized macro blocks using said variable length code.
Claim 6
Dependent Claim
83 words
The method of claim 1; wherein said transformed macro blocks also contain high frequency AC components of said digital image signal; said sync block also has at least one high frequency AC component area at a predetermined position; and, in said step of forming, at least some of the encoded data corresponding to the high frequency AC components of said approximately integer number of transformed macro blocks in the sync block are placed in said at least one high frequency AC component area.
Claim 7
Dependent Claim
33 words
The method of claim 6; wherein said sync block also includes a data area, and said at least one high frequency AC component area is located near the start of said data area.
Claim 8
Dependent Claim
218 words
The method of claim 1; wherein said transformed macro blocks are comprised of a predetermined number of transformed image data blocks which each contain AC component data representing high frequency AC components and said low frequency AC components; the number of said low frequency AC component areas in said sync block is equal to said predetermined number of transformed image data blocks in said transformed macro block; said sync block also has at least one high frequency AC component area at least at one predetermined position; and said step of forming includes: first placing AC component data of one of said transformed image data blocks in a transformed macro block into a respective one of said low frequency AC component areas until said respective one of said low frequency AC component areas is filled, next placing further AC component data of said one of said transformed image data blocks which exceeds the capacity of said respective one of said low frequency AC component areas into said high frequency AC component area and unused areas of other of said low frequency AC component areas which contain AC component data for other of said transformed image data blocks, and finally placing as yet unplaced AC component data of said one of said transformed image data blocks into another sync block.
Claim 9
Independent Claim
130 words
An apparatus for encoding a digital image signal, comprising: means for orthogonally transforming said digital image signal into transformed macro blocks containing DC and low frequency AC components of said digital image signal, means for encoding an encoding set comprised of a predetermined number of said transformed macro blocks using a variable length code into an amount of encoded data in accordance with a target amount, and framing means for forming said encoded data corresponding to an approximately integer number of transformed macro blocks into a sync block having a fixed length and also having DC component areas and low frequency AC component areas at predetermined positions, with the encoded data representing said DC and low frequency AC components being in said DC and low frequency AC component areas, respectively.
Claim 10
Dependent Claim
38 words
The apparatus of claim 9; further comprising means for blocking said digital image signal into image data blocks, and means for shuffling a spatial sequence of said image data blocks before said image data blocks are orthogonally transformed.
Claim 11
Dependent Claim
79 words
The apparatus of claim 10; wherein a predetermined number of said image data blocks form a respective shuffling set of macro blocks, and said means for shuffling shuffles central macro blocks of each said shuffling set which correspond to central portions of an image represented by said digital image signal to precede other macro blocks of said shuffling set which correspond to other portions of said image that are less centrally located in said image than said central portions.
Claim 12
Dependent Claim
27 words
The apparatus of claim 9; wherein said means for orthogonally transforming performs a discrete cosine transformation on said digital image signal to produce said transformed macro blocks.
Claim 13
Dependent Claim
57 words
The apparatus of claim 9; wherein said means for encoding includes means for estimating a quantizing number for said encoding set based on said target amount, means for quantizing said macro blocks in said encoding set in accordance with said quantizing number, and means for variable length coding the quantized macro blocks using said variable length code.
Claim 14
Dependent Claim
80 words
The apparatus of claim 9; wherein said transformed macro blocks also contain high frequency AC components of said digital image signal; said sync block also has at least one high frequency AC component area at a predetermined position; and said framing means places at least some of the encoded data corresponding to the high frequency AC components of said approximately integer number of transformed macro blocks in the sync block into said at least one high frequency AC component area.
Claim 15
Dependent Claim
33 words
The apparatus of claim 14; wherein said sync block also includes a data area, and said at least one high frequency AC component area is located near the start of said data area.
Claim 16
Dependent Claim
223 words
The apparatus of claim 9; wherein said transformed macro blocks are comprised of a predetermined number of transformed image data blocks which each contain AC component data representing high frequency AC components and said low frequency AC components; the number of said low frequency AC component areas in said sync block is equal to said predetermined number of transformed image data blocks in said transformed macro block; said sync block also has at least one high frequency AC component area at least at one predetermined position; and said framing means includes: first means for placing AC component data of one of said transformed image data blocks in a transformed macro block into a respective one of said low frequency AC component areas until said respective one of said low frequency AC component areas is filled, second means for placing further AC component data of said one of said transformed image data blocks which exceeds the capacity of said respective one of said low frequency AC component areas into said high frequency AC component area and unused areas of other of said low frequency AC component areas which contain AC component data for other of said transformed image data blocks, and third means for placing as yet unplaced AC component data of said one of said transformed image data blocks into another sync block.
References Cited (Backward Citations)
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