Coding apparatus, coding method, and recording medium

A coding method by a coding apparatus for coding a frame of a moving image on a block basis, the coding method comprising:

• detecting a motion vector of each block of the frame;
• calculating, for a block adjoining a process target block and having a motion vector to be used for coding having been selected, from among blocks in the frame, a difference value between the motion vector detected by the detection and the motion vector of the target block, and calculating a difference value between pixels of a reference block identified by applying the motion vector of the adjoining block to the target block and pixels of the target block;
• determining whether the motion vector to be used for coding the adjoining block has been detected at the time of processing;
• and
• selecting, based on a calculation result by the calculating and a determination result by the determining, a motion vector to be used for coding the target block, from among the motion vector detected from the target block and the motion vector to be used for coding the adjoining block.

A non-transitory computer-readable recording medium storing a program for causing a computer of a coding apparatus for coding a frame of a moving image on a block basis to function as:

• a detection unit configured to detect a motion vector of each block of the frame;
• a calculation unit configured to, for a block adjoining a process target block and having a motion vector to be used for coding having been selected, from among blocks in the frame, calculate a difference value between the motion vector detected by the detection unit and the motion vector of the target block and calculate a difference value between pixels of a reference block identified by applying the motion vector of the adjoining block to the target block and pixels of the target block;
• a determination unit configured to determine whether the motion vector to be used for coding the adjoining block has been detected at the time of processing;
• and
• a motion vector selection unit configured to, based on a calculation result by the calculation unit and a determination result by the determination unit, select a motion vector to be used for coding the target block, from among the motion vector detected from the target block and the motion vector to be used for coding the adjoining block.