Picture decoding device, picture decoding method and picture decoding program

Patent metadata

Field	Value
Publication number	US-10063885-B2
Application number	US-201815936687-A
Country	US
Kind code	B2
Filing date	Mar 27, 2018
Priority date	Mar 29, 2013
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

In a picture coding device for coding picture signals including a brightness signal and a color-difference signal in a block unit using intra-prediction and coding information regarding an intra-prediction mode, when aspect ratios of pixels of the brightness signal and the color-difference signal are different from each other, a bitstream generator converts a mode number of a first intra-color-difference prediction mode used when the aspect ratios are equal to each other into a scaled mode number and derives a second intra-color-difference prediction mode used when the aspect ratios are different from each other.

First claim

What is claimed is:

1. A picture decoding device for decoding information regarding an intra-prediction mode in a prediction block unit and decoding picture signals including a brightness signal and a color-difference signal in a conversion block unit using intra-prediction, comprising:
an intra-brightness prediction mode decoder that decodes a first syntax element regarding an intra-prediction mode of the brightness signal from a bitstream in which information regarding an intra-brightness prediction mode showing an intra-prediction method of a prediction block of a bright signal is coded and derives the intra-brightness prediction mode from the first syntax element;
an intra-color-difference prediction mode decoder that decodes a second syntax element regarding an intra-color-difference prediction mode of the color-difference signal from the bitstream in which information regarding an intra-color-difference prediction mode showing an intra-prediction method of a prediction block of the color-difference signal is coded and derives a first intra-color-difference prediction mode from the second syntax element and the intra-brightness prediction mode;
a brightness signal intra-predictor that predicts a brightness signal of a conversion block of the brightness signal from a surrounding brightness signal of the conversion block of the brightness signal, according to the intra-brightness prediction mode specified for each prediction block of the brightness signal; and
a color-difference signal intra-predictor that predicts a color-difference signal of a conversion block of the color-difference signal from a surrounding color-difference signal of the conversion block of the color-difference signal, according to the intra-color-difference prediction mode specified for each prediction block of the color-difference signal, wherein
when aspect ratios of pixels of the brightness signal and the color-difference signal are different from each other, the intra-color-difference prediction mode decoder derives a second intra-color-difference prediction mode from the first intra-color-difference prediction mode, based on a conversion table in which an intra-prediction mode of a prediction direction of an angle close to an angle derived by scaling an angle of a prediction direction corresponding to the first intra-color-difference prediction mode used when the aspect ratios are equal to each other by a predetermined scaling factor is set as the second intra-color-difference prediction mode used when the aspect ratios are different from each other,
in the conversion table, if a mode number of the first intra-color-difference prediction mode is a mode number showing vertical prediction, then a mode number of the second intra-color-difference prediction mode is set equal to the mode number showing vertical prediction,
in the conversion table, if the mode number of the first intra-color-difference prediction mode is not the mode number showing vertical prediction, then the mode number of the second intra-color-difference prediction mode is set excluding the mode number showing vertical prediction,
when the aspect ratios are equal to each other, the color-difference signal intra-predictor predicts a color-difference signal of the conversion block of the color-difference signal from a signal of a surrounding conversion block, according to the first intra-color-difference prediction mode, and, when the aspect ratios are different, the color-difference signal intra-predictor predicts a color-difference signal of the conversion block of the color-difference signal from a signal of a surrounding conversion block, according to the second intra-color-difference prediction mode.

2. A picture decoding method for decoding information regarding an intra-prediction mode in a prediction block unit and decoding picture signals including a brightness signal and a color-difference signal in a conversion block unit using intra-prediction, comprising:
decoding a first syntax element regarding an intra-prediction mode of the brightness signal from a bitstream in which information regarding an intra-brightness prediction mode showing an intra-prediction method of a prediction block of a bright signal is coded and derives the intra-brightness prediction mode from the first syntax element;
decoding a second syntax element regarding an intra-color-difference prediction mode of the color-difference signal from the bitstream in which information regarding an intra-color-difference prediction mode showing an intra-prediction method of a prediction block of the color-difference signal is coded and derives a first intra-color-difference prediction mode from the second syntax element and the intra-brightness prediction mode;
predicting a brightness signal of a conversion block of the brightness signal from a surrounding brightness signal of the conversion block of the brightness signal, according to an intra-brightness prediction mode specified for each prediction block of the brightness signal; and
predicting a color-difference signal of a conversion block of the color-difference signal from a surrounding color-difference signal of the conversion block of the color-difference signal, according to the intra-color-difference prediction mode specified for each prediction block of the color-difference signal, wherein
when aspect ratios of pixels of the brightness signal and the color-difference signal are different from each other, deriving a second intra-color-difference prediction mode from the first intra-color-difference prediction mode, based on a conversion table in which an intra-prediction mode of a prediction direction of an angle close to an angle derived by scaling an angle of a prediction direction corresponding to the first intra-color-difference prediction mode used when the aspect ratios are equal to each other by a predetermined scaling factor is set as the second intra-color-difference prediction mode used when the aspect ratios are different from each other,
in the conversion table, if a mode number of the first intra-color-difference prediction mode is a mode number showing vertical prediction, then a mode number of the second intra-color-difference prediction mode is set equal to the mode number showing vertical prediction,
in the conversion table, if the mode number of the first intra-color-difference prediction mode is not the mode number showing vertical prediction, then the mode number of the second intra-color-difference prediction mode is set excluding the mode number showing vertical prediction,
when the aspect ratios are equal to each other, predicting a color-difference signal of the conversion block of the color-difference signal from a signal of a surrounding conversion block, according to the first intra-color-difference prediction mode, and, when the aspect ratios are different, predicting a color-difference signal of the conversion block of the color-difference signal from a signal of a surrounding conversion block, according to the second intra-color-difference prediction mode.

3. Anon-transitory computer-readable recording medium having embodied thereon a picture decoding program for decoding information regarding an intra-prediction mode in a prediction block unit and decoding picture signals including a brightness signal and a color-difference signal in a conversion block unit using intra-prediction, the picture decoding program causing a computer to execute:
decoding a first syntax element regarding an intra-prediction mode of the brightness signal from a bitstream in which information regarding an intra-brightness prediction mode showing an intra-prediction method of a prediction block of a bright signal is coded and derives the intra-brightness prediction mode from the first syntax element;
decoding a second syntax element regarding an intra-color-difference prediction mod

Assignees

• Jvc Kenwood Corp

Inventors

• Nakamura Hiroya
• Ueda Motoharu
• Fukushima Shigeru
• Kumakura Toru

Classifications

• H04N19/109 Primary

  among a plurality of temporal predictive coding modes · CPC title

• H04N19/463

  by compressing encoding parameters before transmission · CPC title

• H04N19/593 Primary

  involving spatial prediction techniques · CPC title

• H04N19/186

  the unit being a colour or a chrominance component · CPC title

• H04N19/503

  involving temporal prediction (adaptive coding with adaptive selection between spatial and temporal predictive coding H04N19/107; adaptive coding with adaptive selection among a plurality of temporal predictive coding modes H04N19/109) · CPC title