Patent ID: 9363521
Filing Date: 2016-06-07
CPC Classification: H04N

Claim Text:
1. A picture coding device that performs intra prediction coding of a picture signal including a luma signal and a chroma signal in units of blocks and codes information relating to an intra prediction mode, the picture coding device comprising: a luma signal intra prediction unit configured to set first to fourth prediction blocks of luma signals acquired by partitioning luma signals of a coding block horizontally and vertically and predict a luma signal based on a coded neighboring block of luma signals in accordance with luma intra prediction modes of the first to fourth prediction blocks of luma signals derived based on information relating to luma intra prediction modes for prediction blocks of luma signals respectively, in a case where a partition mode in which luma signals are partitioned horizontally and vertically is set when an intra prediction of the picture signal is made in coding units; a chroma signal intra prediction unit configured to set a prediction block of chroma signals without partitioning chroma signals of the coding block and predict a chroma signal based on a coded neighboring block of chroma signals in accordance with a chroma intra prediction mode in a case where the partition mode is set, and a chroma format is 4:2:0, the chroma intra prediction mode being derived based on information relating to a chroma intra prediction mode and the luma intra prediction mode of the first prediction block of luma signals; and a bitstream constructing unit configured to code information relating to intra prediction modes and construct a bitstream in which coding information relating to the intra prediction modes is arranged within a coding block, said bitstream including a syntax element relating to a luma intra prediction mode of the first prediction block of luma signals, a syntax element relating to a luma intra prediction mode of the second prediction block of luma signals, a syntax element relating to a luma intra prediction mode of the third prediction block of luma signals, a syntax element relating to a luma intra prediction mode of the fourth prediction block of luma signals, and a syntax element relating to a chroma intra prediction mode of the prediction block of chroma signals that is located at a reference position that is the same as the position of the first prediction block of luma signals, and said information relating to intra prediction modes including information relating to luma intra prediction modes of the first to fourth prediction blocks of luma signals and information relating to a chroma intra prediction mode of the prediction block of chroma signals, wherein the chroma signal intra prediction unit sets a value indicating the chroma intra prediction mode of the prediction block of chroma signals within the coding block to be equal to a value indicating the luma intra prediction mode of the first prediction block of luma signals within the coding block, in a mode of setting the chroma intra prediction mode depending on the luma intra prediction mode, wherein the luma signal intra prediction unit, the chroma signal intra prediction unit, and the bitstream constructing unit are implemented using hardware, memory storing firmware, or a computer with software.