Variable length coding method and variable length decoding method

• US 7,411,526 B2
• Filed: 07/31/2006
• Issued: 08/12/2008
• Est. Priority Date: 11/22/2001
• 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: Abe, Kiyofumi, Kadono, Shinya, Kondo, Satoshi, Hagai, Makoto
• Primary Examiner(s): Mai; Lam T
• Application Number:
  US11/495,601
• Publication Number:
  US 20060261987A1
• Time in Patent Office: 743 Days
• Field of Search: 341 50- 70
• US Class Current: 341/67
• CPC Class Codes: G06T 9/005 Statistical coding, e.g. Huffman, run length coding
• CPC Class Codes: G11B 20/1426 conversion to or from block codes or representations thereof
• CPC Class Codes: H03M 5/145 Conversion to or from block codes or representations thereof
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code
• CPC Class Codes: H03M 7/46 Conversion to or from run-length codes, i.e. by representing the number of consecutive digits, or groups of digits, of the same kind by a code word and a digit indicative of that kind
• 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 19/134 characterised by the element, parameter or criterion affecting or controlling the adaptive coding
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/162 User input
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/18 the unit being a set of transform coefficients
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/69 involving reversible variable length codes [RVLC]
• CPC Class Codes: H04N 19/89 involving methods or arrangements for detection of transmission errors at the decoder
• CPC Class Codes: H04N 19/93 Run-length coding

Abstract

An image coding apparatus provides a run-length encoding unit RLE1 that subjects quantized coefficients which are obtained by quantizing frequency components of an image signal to a variable length coding process by using a run value Run that indicates the number of successive zero coefficients and a level value Lev that indicates a value of a non-zero coefficient following the zero coefficients. The run-length encoding unit RLE1 includes a reordering unit Lreodr for reordering level values Lev; a variable length coder LVLC for coding reordered level values ROLev by using a code table that is selected according to the value of a quantization parameter QP; a reordering unit Rreodr for reordering run values Run from high frequency component of the quantized coefficients to low frequency component; and a variable length coder RVLC for coding reordered run values RORun by using a code table that is selected according to the number of already-processed run values.

Claims

1. A method for decoding a coded block image, the method comprising:

decoding coded transform coefficients from a high frequency component toward a low frequency component, in accordance with information that represents a total number of undecoded transform coefficients, to obtain decoded transform coefficients, wherein the undecoded transform coefficients are transform coefficients which have not been decoded;

inverse scanning the decoded transform coefficients into a two-dimensional array of transform coefficients; and

inverse quantizing and inverse frequency transforming the two-dimensional array of transform coefficients to obtain a reconstructed block image.