Method of detecting a motion vector in an image coding apparatus

• US 5,398,078 A
• Filed: 10/30/1992
• Issued: 03/14/1995
• Est. Priority Date: 10/31/1991
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yamakage, Tomoo, Masuda, Tadaaki, Uetani, Yoshiharu, Odaka, Toshinori, Oku, Tadahiro
• Primary Examiner(s): Chin, Tommy P.
• Assistant Examiner(s): LEE, RICHARD J
• Application Number:
  US07/969,351
• Time in Patent Office: 865 Days
• Field of Search: 358/105, 358/133, 358/136
• US Class Current: 348/699
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/124 Quantisation
• 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 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/142 Detection of scene cut or scene change
• CPC Class Codes: H04N 19/146 Data rate or code amount at the encoder output
• CPC Class Codes: H04N 19/149 by estimating the code amount by means of a model, e.g. mathematical model or statistical model
• CPC Class Codes: H04N 19/15 by monitoring actual compressed data size at the memory before deciding storage at the transmission buffer
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/44 Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• CPC Class Codes: H04N 19/51 Motion estimation or motion compensation
• CPC Class Codes: H04N 19/53 Multi-resolution motion estimation; Hierarchical motion estimation
• CPC Class Codes: H04N 19/59 involving spatial sub-sampling or interpolation, e.g. alteration of picture size or resolution
• CPC Class Codes: H04N 19/60 using transform coding
• CPC Class Codes: H04N 19/61 in combination with predictive coding
• CPC Class Codes: H04N 19/91 Entropy coding, e.g. variable length coding [VLC] or arithmetic coding

Abstract

A method of detecting a motion vector in an image coding apparatus, including blocking an input image block to be coded into a plurality of input blocks each consisting of a plurality of pixels; sub-sampling a coded image signal to obtain a coded and sub-sampled image signal; sub-sampling the input image block at a predetermined pixel interval to obtain a sub-sampled input block; searching a primary block most correlated with the sub-sampled input block from the coded and sub-sampled image signal in a predetermined range, to output a primary motion vector which indicates the primary block most correlated with the sub-sampled input blocks; and controlling at least one of a central position of a searching area and a searching pel accuracy in accordance with a type of the primary motion vector, to search a secondary block most correlated with one of the input blocks from a coded image signal, to obtain a secondary motion vector.

Claims

1. A method of detecting a motion vector, comprising:

a first step for blocking an input image signal to be coded into a plurality of input blocks each consisting of a plurality of pixels;

a second step for sub-sampling the input image signal at a predetermined pixel interval, to obtain a sub-sampled image signal;

a third step for obtaining a sub-sampled input block from the sub-sampled image signal;

a fourth step for searching in a predetermined range the sub-sampled image signal which has already been subjected to a coding process for a primary block most correlated with the sub-sampled input block, to output a primary motion vector which indicates the primary block most correlated with the sub-sampled input block; and

a fifth step for controlling at least one of a central position of a searching area and a searching pel accuracy in accordance with a type of the primary motion vector, to search for a secondary block most correlated with one of the input blocks, to output a secondary motion vector.

2. A method according to claim 1, wherein the fifth step includes a step of controlling the central position so as to locate it on a position indicated by the primary motion vector when the primary motion vector is on a central position of a primary motion vector searching range.

3. A method according to claim 1, wherein the fifth step includes a step of controlling a central position of a secondary motion vector searching range so as to separate it from a position which is indicated by the primary motion vector so that an overlapping portion of the secondary motion vector searching range with a primary motion vector searching range is decreased when the primary motion vector is on a peripheral portion of the primary motion vector searching range.

4. A method according to claim 1, wherein the fifth step includes a step of setting a searching pel accuracy at a half pixel or finer, for searching the secondary motion vector from among a narrow area whose central position is indicated by the primary motion vector when the primary motion vector is on a central position of primary motion vector searching range.

5. A method according to claim 1, wherein the second step includes a step of sub-sampling a coded image signal with a phase that differs from a sub-sampling phase of the input image block.