Picture encoding device, picture encoding method, picture encoding program, picture decoding device, picture decoding method, and picture decoding program

A picture encoding method with a motion compensation prediction comprising:

• selecting a plurality of blocks each having one or two pieces of motion information containing at least information about a motion vector and information about a reference picture from a plurality of neighboring encoded blocks of a encoding target block and constructing a candidate list containing candidates of the motion information used for the motion compensation prediction from the motion information of the selected blocks;
• deriving from a first candidate contained in the candidates first motion information in a first direction;
• deriving from a second candidate different from the first candidate contained in the candidates second motion information in a second direction different from the first direction;
• generating a first new candidate of the motion information by combining the first motion information and the second motion information;
• selecting one candidate from the candidates contained in the candidate list;
• encoding candidate identification information to identify the selected candidate in the candidate list;
• deriving from the second candidate third motion information in the first direction;
• deriving from the first candidate fourth motion information in the second direction;
• and
• generating a second new candidate of the motion information by combining the third motion information and the fourth motion information, wherein
• each of the first new candidate and the second new candidate has motion information of a combination of different directions of the first candidate and the second candidate, and
• the candidate list includes at least one new candidate such that the number of the candidates does not exceed a set maximum number.

A non-transitory computer-readable recording medium having embedded thereon a picture encoding program with a motion compensation prediction, the picture encoding program causing a computer to execute:

• selecting a plurality of blocks each having one or two pieces of motion information containing at least information about a motion vector and information about a reference picture from a plurality of neighboring encoded blocks of a encoding target block and constructing a candidate list containing candidates of the motion information used for the motion compensation prediction from the motion information of the selected blocks;
• deriving from a first candidate contained in the candidates first motion information in a first direction;
• deriving from a second candidate different from the first candidate contained in the candidates second motion information in a second direction different from the first direction;
• generating a first new candidate of the motion information by combining the first motion information and the second motion information;
• selecting one candidate from the candidates contained in the candidate list;
• encoding candidate identification information to identify the selected candidate in the candidate list;
• deriving from the second candidate third motion information in the first direction;
• deriving from the first candidate fourth motion information in the second direction;
• and
• generating a second new candidate of the motion information by combining the third motion information and the fourth motion information, wherein
• each of the first new candidate and the second new candidate has motion information of a combination of different directions of the first candidate and the second candidate, and
• the candidate list includes at least one new candidate such that the number of the candidates does not exceed a set maximum number.