Method and apparatus for deriving motion vector

An encoding apparatus for an image encoding, the encoding apparatus comprising:

• a memory;
• and
• at least one processor connected to the memory, the at least one processor configured to:
• derive a temporary reference motion vector for a current block included in a current picture;
• derive a reference motion vector for the current block by applying clipping to the temporary reference motion vector;
• derive a motion vector for the current block based on the reference motion vector;
• derive prediction samples for the current block based on the motion vector for the current block;
• and
• encode image information including information on the prediction samples,
• wherein the reference motion vector is derived based on an equation below,
• mv=Clip3(−217,217−1,mv′), and
• wherein the mv′ in the equation represents the temporary reference motion vector, and the my represents the reference motion vector.

An apparatus for transmitting data for an image, the apparatus comprising:

• at least one processer configured to obtain a bitstream for the image, wherein the bitstream is generated based on deriving a temporary reference motion vector for a current block included in a current picture, deriving a reference motion vector for the current block by applying clipping to the temporary reference motion vector, deriving a motion vector for the current block based on the reference motion vector, deriving prediction samples for the current block based on the motion vector for the current block and encoding image information including information on the prediction samples;
• and
• a transmitter configured to transmit the data comprising the bitstream,
• wherein the reference motion vector is derived based on an equation below,
• mv=Clip3(−217,217−1,mv′), and
• wherein the mv′ in the equation represents the temporary reference motion vector, and the my represents the reference motion vector.