Image encoder

• US 6,608,939 B2
• Filed: 05/18/2001
• Issued: 08/19/2003
• Est. Priority Date: 11/07/1996
• Status: Expired due to Term

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Matsumoto, Taisuke
• Primary Examiner(s): Do, Anh Hong
• Application Number:
  US09/859,636
• Publication Number:
  US 20010022855A1
• Time in Patent Office: 823 Days
• Field of Search: 382/232, 382/238, 382/236, 382/243, 382/260, 375/240.1, 375/240.2, 709/247, 348/14.12, 348/14.08
• US Class Current: 382/238
• CPC Class Codes: H04N 19/13 Adaptive entropy coding, e.g. adaptive variable length coding [AVLC] or context adaptive binary arithmetic coding [CABAC]
• CPC Class Codes: H04N 19/157 Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/196 being specially adapted for the computation of encoding parameters, e.g. by averaging previously computed encoding parameters processing of motion vectors H04N19/513
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 19/463 by compressing encoding parameters before transmission
• CPC Class Codes: H04N 19/593 involving spatial prediction techniques
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

An image coding method codes each block of a digital image divided into two-dimensional blocks, each block having a plurality of pixels. A coding mode for a target block is determined to output mode information of the target block. A codeword of the mode information of the target block is output, the codeword being determined based on a combination of the mode information of the target block and the mode information of previously coded blocks at a periphery of the target block, or a combination of the mode information of the target block and temporary mode information replacing the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image. Pixel data in the target block is coded according to the mode information of the target block.

Claims

1. An image coding method for coding each block of a digital image divided into two-dimensional blocks, each block having a plurality of pixels, the method comprising:

determining a coding mode for a target block to output mode information of the target block;

outputting a codeword of the mode information of the target block, the codeword being determined based on a combination of the mode information of the target block and the mode information of previously coded blocks at a periphery of the target block, or a combination of the mode information of the target block and temporary mode information as a substitute for the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image; and

coding pixel data in the target block according to the mode information of the target block.

2. An image coding method for coding each block of a digital image divided into two-dimensional blocks, each block having a plurality of pixels, the method comprising:

determining a coding mode for a target block to output mode information of the target block;

fetching a codeword of the mode information of the target block from a codeword table to output, based on a combination of the mode information of the target block and the mode information of previously coded blocks at a periphery of the target block including temporary mode information as the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image, the codeword table having codewords, each codeword being determined based on a combination of the mode information of the target block and the mode information of the previously coded blocks at the periphery of the target block;

or a combination of the mode information of the target block and temporary mode information as a substitute for the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image; and

coding pixel data in the target block according to the mode information of the target block.

3. An image coding apparatus for coding each block of a digital image divided into two-dimensional blocks, each block having a plurality of pixels, said apparatus comprising:

a mode information determining section that is configured to determine a coding mode for a target block to output information of the target block;

a mode information coding section that is configured to output, as a codeword of the mode information of the target block, the codeword that is determined based on a combination of the mode information of the target block and the mode information of previously coded blocks at the periphery of the target block, or a combination of the mode information of the target block and temporary mode information as a substitute for the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image; and

a block data coding section that is configured to code pixel data in the target block according to the mode information of the target block.

4. An image coding apparatus for coding each block of a digital image divided into two-dimensional blocks, each block having a plurality of pixels, said apparatus comprising:

a mode information determining section that is configured to determine a coding mode for a target block to output mode information of the target block;

a mode information coding section that is configured to fetch and output a codeword of the mode information of the target block from a codeword table, based on a combination of the mode information of the target block and mode information of previously coded blocks at the periphery of the target block including temporary mode information as the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image, said table having codewords, each codeword being determined based on a combination of the mode information of the target block and the mode information of the previously coded blocks at the periphery of the target block, or a combination of the mode information of the target block and temporary mode information as a substitute for the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image; and

a block data coding section that is configured to code pixel data in the target block according to the mode information of the target block.

5. A computer-readable recording medium with an image coding program stored therein, said program being executed by a computer to code each block of a digital image divided into two-dimensional blocks, each block having a plurality of pixels, said program comprising:

determining a coding mode for a target block to output mode information of the target block;

outputting, as a codeword of the mode information of the target block, the codeword that is determined based on a combination of the mode information of the target block and the mode information of previously coded blocks at the periphery of the target block, or a combination of the mode information of the target block and temporary mode information as a substitute for the mode information of the blocks at the periphery of the target block when the blocks at the periphery are out of an image; and

coding pixel data in the target block according to the mode information of the target block.