Patent ID: 11882308
Assignee: KDDI CORPORATION
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H | IPC H

Claim 2:
3. An image processing system including an image encoding device and an image decoding device, wherein
the image encoding device and the image decoding device include a prediction unit configured to generate a prediction signal included in a prediction block based on a motion vector;
the prediction unit is configured to perform refinement processing of setting a search range based on a reference position specified by the motion vector, specifying a corrected reference position having the smallest predetermined cost from the search range, and correcting the motion vector based on the corrected reference position, when a predetermined condition is satisfied;
wherein, in the refinement processing, the prediction unit is configured to:
select first candidate positions from the search range;
select at least one second candidate position from the first candidate positions and the reference position;
select only the reference position as the second candidate position when the smallest predetermined cost of the reference position is smaller than a certain percentage of a minimum value of the first candidate positions, the certain percentage being less than 100% of the minimum value of the first candidate positions;
specify pixels adjacent to the second candidate position as third candidate positions, the third candidate position including half pixels interpolated by integer pixels; and
specify a position having the smallest predetermined cost from the first candidate positions, the second candidate position, the third candidate positions as the corrected reference position;

the predetermined condition includes a condition that the prediction block is a block that performs bidirectional prediction, one reference frame is a frame that is temporally earlier than a target frame, and the other reference frame is a frame that is temporally future than the target frame;
a displacement between the first candidate position and the reference position in the one reference frame has a same absolute value with an opposite sign of a displacement between the first candidate position and the reference position in the other reference frame;
a displacement between the second candidate position and the reference position in the one reference frame has a same absolute value with an opposite sign of a displacement between the second candidate position and the reference position in the other reference frame;
a displacement between the third candidate position and the reference position in the one reference frame has a same absolute value with an opposite sign of a displacement between the third candidate position and the reference position in the other reference frame; and
when a block size of the prediction block is larger than a predetermined block size, the prediction unit divides the prediction block into sub-block groups and performs the refinement processing for each sub-block.