Image decoding method, image coding method, image decoding apparatus, image coding apparatus, and image coding and decoding apparatus

• US 9,525,881 B2
• Filed: 08/27/2015
• Issued: 12/20/2016
• Est. Priority Date: 06/30/2011
• Status: Active Grant

• Current Assignee: Sun Patent Trust
• Original Assignee: Sun Patent Trust
• Inventors: Sasai, Hisao, Nishi, Takahiro, Shibahara, Youji, Sugio, Toshiyasu, Tanikawa, Kyoko, Matsunobu, Toru
• Primary Examiner(s): Dang, Duy M
• Application Number:
  US14/837,546
• Publication Number:
  US 20150373335A1
• Time in Patent Office: 481 Days
• US Class Current: 1/1
• CPC Class Codes: H04N 19/103 Selection of coding mode or of prediction mode
• CPC Class Codes: H04N 19/105 Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• 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 19/136 Incoming video signal characteristics or properties
• CPC Class Codes: H04N 19/139 Analysis of motion vectors, e.g. their magnitude, direction, variance or reliability
• 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 19/583 Motion compensation with overlapping blocks
• CPC Class Codes: H04N 19/70 characterised by syntax aspects related to video coding, e.g. related to compression standards
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

The image coding method includes: determining a context in a current block in the image, from among a plurality of contexts; and performing arithmetic coding on the control parameter for the current block to generate a bitstream corresponding to the current block, wherein in the determining: the context is determined under a condition that control parameters of neighboring blocks of the current block are used, when the signal type is a first type, the neighboring blocks being a left block and an upper block of the current block; and the context is determined under a condition that the control parameter of the upper block is not used, when the signal type is a second type, and the second type is (i) “merge_flag”, (ii) “ref_idx_l0” or “ref_idx_l1”, (iii) “inter_pred_flag”, (iv) “mvd_l0” or “mvd_l1”, (v) “no_residual_data_flag”, (vi) “intra_chroma_pred_mode”, (vii) “cbf_luma”, and (viii) “cbf_cb” or “cbf_cr”.

Claims

1. A coding and decoding apparatus for coding a first control parameter for controlling coding of a first image and decoding a second control parameter for controlling decoding of a second image, the coding and decoding apparatus comprising:

processing circuitry; and

a memory,

wherein the processing circuitry performs the following;

determining a first context for a first current block in the first image, from among a plurality of first contexts stored in the memory; and

performing arithmetic coding on the first control parameter for the first current block to generate a first bitstream, using the determined first context,

wherein the determining of a first context includes;

determining a first signal type under which the first control parameter for the first current block is classified;

determining the first context by using both of coded first control parameters for a first left block and a first upper block, when the first signal type is a first type, the first left block being a neighboring block to the left of the first current block, and the first upper block being a neighboring block on top of the first current block; and

determining the first context by using a predetermined first fixed value, without using any of the coded first control parameters for the first left block and the first upper block, when the first signal type is a second type different from the first type,

wherein one of a first split flag and a first skip flag is classified under the first type, the first split flag indicating whether or not the first current block is partitioned into a plurality of blocks, and the first skip flag indicating whether or not the first current block is to be skipped,

wherein a first difference parameter and a first residual flag are classified under the second type, the first difference parameter indicating a difference between a first motion vector and a first motion vector predictor of the first current block, and the first residual flag indicating whether or not luma coefficient data and chroma coefficient data are included in the first current block,

wherein the processing circuitry further performs the following;

determining a second context for a second current block in the second image, from among a plurality of second contexts stored in the memory; and

performing arithmetic decoding on a second bitstream corresponding to the second current block, using the determined second context to obtain the second control parameter for the second current block,

wherein the determining of a second context includes;

determining a second signal type under which the second control parameter for the second current block is classified;

determining the second context by using both of decoded second control parameters for a second left block and a second upper block, when the second signal type is a third type, the second left block being a neighboring block to the left of the second current block, and the second upper block being a neighboring block on top of the second current block; and

determining the second context by using a predetermined second fixed value, without using any of the decoded second control parameters for the second left block and the second upper block, when the second signal type is a fourth type different from the third type,

wherein one of a second split flag and a second skip flag is classified under the third type, the second split flag indicating whether or not the second current block is partitioned into a plurality of blocks, and the second skip flag indicating whether or not the second current block is to be skipped, and

wherein a second difference parameter and a second residual flag are classified under the fourth type, the second difference parameter indicating a difference between a second motion vector and a second motion vector predictor of the second current block, and the second residual flag indicating whether or not luma coefficient data and chroma coefficient data are included in the second current block.