Spatial prediction method, image decoding method, and image coding method

• US 9,961,367 B2
• Filed: 02/07/2017
• Issued: 05/01/2018
• Est. Priority Date: 04/12/2010
• Status: Active Grant

• Current Assignee: Sun Patent Trust
• Original Assignee: Sun Patent Trust
• Inventors: Drugeon, Virginie, Shibahara, Youji, Nishi, Takahiro, Sasai, Hisao, Tanikawa, Kyoko
• Primary Examiner(s): Do, Anh H
• Application Number:
  US15/426,201
• Publication Number:
  US 20170150177A1
• Time in Patent Office: 448 Days
• Field of Search: 382238, 382232, 382233, 382241, 382168, 348241, 37524012
• CPC Class Codes: H04N 19/11 among a plurality of spatial predictive coding modes
• CPC Class Codes: H04N 19/136 Incoming video signal characteristics or properties
• 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 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/182 the unit being a pixel
• CPC Class Codes: H04N 19/42 characterised by implementation details or hardware specially adapted for video compression or decompression, e.g. dedicated software implementation H04N19/635 takes precedence
• 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 19/593 involving spatial prediction techniques

Abstract

A spatial prediction method capable of reducing the complexity of spatial prediction includes: detecting an edge (E) overlapping the current block by obtaining a horizontal gradient (Gy) and a vertical gradient (Gx) between pixels within a block adjacent to the current block; calculating an integer slope of the edge; determining, for each pixel position within the current block, a sub-pel position being an intersection between (i) a line that has the integer slope and passes through the pixel position and (ii) a boundary of the adjacent block; and predicting, for each pixel position, a pixel value at the pixel position based on a pixel value interpolated in the sub-pel position, wherein the boundary of the adjacent block is a row or a column that is the closest to the current block, among rows or columns of pixels included in the adjacent block.

Claims

1. An image coding apparatus which codes an image per block included in the image, the image coding apparatus comprising:

a processor; and

a non-transitory memory having a computer program stored thereon, the computer program causing the processor to execute operations including;

calculating an integer slope indicating an integer value of a slope, based on at least one of a horizontal gradient and a vertical gradient;

determining, for each of pixel positions within a current block to be coded, a sub-pel position that is an intersection between a line having the integer slope and passing through the pixel position within the current block and a boundary of a block adjacent to the current block;

generating a predicted block by predicting, for each of the pixel positions within the current block, a pixel value at the pixel position, based on a pixel value interpolated in the sub-pel position determined for the pixel position; and

coding the current block by subtracting the predicted block from the current block,

wherein in the calculating, a result of a division with reference to a division table stored in a memory is obtained, and the integer slope is calculated using the obtained result of the division, the division using, as a divisor, a value indicating the one of the horizontal gradient and the vertical gradient, the division table indicating, for each predetermined value, a result of a division of a value scaled by a c-th power of 2, using the predetermined value as a divisor, where c is a positive integer, and

wherein in the generating, the pixel value interpolated in the sub-pel position is calculated by multiplying the integer slope generated by scaling by a coordinate value horizontal or vertical to a pixel position to be predicted within the current block, and shifting the multiplied integer slope right by c bits.