Image coding device, image coding method, and image coding integrated circuit

An image encoding apparatus that compression-encodes an image in units of blocks having a predetermined size, the image encoding apparatus having a first encoding mode in which motion information of an encoding-target block is not encoded and the motion information of the encoding-target block is calculated based on motion information of a plurality of adjacent blocks that are adjacent to the encoding-target block, the image encoding apparatus comprising:

• a motion vector speculative calculation unit that speculatively calculates, in case the encoding-target block is to be encoded in the first encoding mode, one or more candidates of motion information for encoding the encoding-target block in the first encoding mode, each of the one or more candidates corresponding to one of some or all of possible encoding modes for encoding an encoding mode undetermined block, the encoding mode undetermined block being one of the adjacent blocks;
• and
• a motion vector determination unit that determines, if an encoding mode for encoding the encoding mode undetermined block is determined from among the some or all of possible encoding modes, one of the one or more candidates that corresponds to the determined encoding mode for encoding the encoding mode undetermined block as the motion information for encoding the encoding target block in the first encoding mode.

An image encoding method that causes a programmed computer to compression-encode an image in units of blocks having a predetermined size, the image encoding method having a first encoding mode in which motion information of an encoding-target block is not encoded and the motion information of the encoding-target block is calculated based on motion information of a plurality of adjacent blocks that are adjacent to the encoding-target block, the image encoding method comprising:

• speculatively calculating, in case the encoding-target block is to be encoded in the first encoding mode, one or more candidates of motion information for encoding the encoding-target block in the first encoding mode, each of the one or more candidates corresponding to one of some or all of possible encoding modes for encoding an encoding mode undetermined block, the encoding mode undetermined block being one of the adjacent blocks;
• and
• determining, if an encoding mode for encoding the encoding mode undetermined block is determined from among the some or all of possible encoding modes, one of the one or more candidates that corresponds to the determined encoding mode for encoding the encoding mode undetermined block as the motion information for encoding the encoding target block in the first encoding mode.