Method and apparatus for image coding/decoding

An image encoding method comprising:

• generating a prediction block by performing inter prediction;
• and
• performing entropy encoding of a residual block corresponding to a difference between a current input block and the prediction block predicted by the inter prediction,
• wherein a prediction motion vector corresponding to the prediction block is included in a motion vector candidate list,
• wherein the motion vector candidate list comprises any one or any combination of any two or more of a spatial motion vector candidate, a temporal motion vector candidate, and a specific motion vector candidate,
• wherein the motion vector candidate list is configured by
• deriving the spatial motion vector candidate,
• deriving the temporal motion vector candidate except when two derived spatial motion vector candidates are present and different from each other, and
• adding either one or both of the derived spatial motion vector candidate and the derived temporal motion vector candidate to the motion vector candidate list, and
• wherein in response to a number of motion vector candidates in the motion vector candidate list being smaller than a maximum number of motion vector candidates, the specific motion vector candidate is repeatedly added to the motion vector candidate list until the number of motion vector candidates in the motion vector candidate list reaches the maximum number of motion vector candidates, based on only the maximum number of motion vector candidates and the number of motion vector candidates in the motion vector candidate list,
• wherein the adding either one or both of the derived spatial motion vector candidate and the derived temporal motion vector candidate to the motion vector candidate list carries out an operation of checking the same motion vector candidate only on the spatial motion vector candidates for removing the same motion vector candidate.

A non-transitory computer-readable storage medium storing a bitstream, the bitstream comprising:

• information for determining a prediction motion vector based on a motion vector candidate list,
• wherein the motion vector candidate list comprises any one or any combination of any two or more of a spatial motion vector candidate, a temporal motion vector candidate, and a specific motion vector candidate,
• wherein the motion vector candidate list is configured by
• deriving the spatial motion vector candidate,
• deriving the temporal motion vector candidate except when two derived spatial motion vector candidates are present and different from each other, and
• adding either one or both of the derived spatial motion vector candidate and the derived temporal motion vector candidate to the motion vector candidate list, and
• wherein in response to a number of motion vector candidates in the motion vector candidate list being smaller than a maximum number of motion vector candidates, the specific motion vector candidate is repeatedly added to the motion vector candidate list until the number of motion vector candidates in the motion vector candidate list reaches the maximum number of motion vector candidates, based on only the maximum number of motion vector candidates and the number of motion vector candidates in the motion vector candidate list,
• wherein the adding either one or both of the derived spatial motion vector candidate and the derived temporal motion vector candidate to the motion vector candidate list carries out an operation of checking the same motion vector candidate only on the spatial motion vector candidates for removing the same motion vector candidate.