Image coding method, image decoding method, image coding apparatus, and image decoding apparatus

摘要

An image coding method includes: deriving a candidate for a motion vector predictor from a neighboring motion vector; adding the candidate to a list; selecting a motion vector predictor from the list; coding a current block; and coding a current motion vector. In the deriving, the candidate is derived according to a first derivation scheme when each of a current reference picture and a neighboring reference picture is determined to be a long-term reference picture, and the candidate is derived according to a second derivation scheme when each of a current reference picture and a neighboring reference picture is determined to be a short-term reference picture.

主权项

1. A motion vector predictor deriving method of deriving a motion vector predictor for each block among blocks of pictures, the motion vector predictor deriving method comprising:
deriving a candidate for a motion vector predictor to be used in coding of a motion vector for a current block to be coded, from a first motion vector for a neighboring block which is included in a current picture including the current block and is adjacent to the current block; adding the derived candidate to a list of candidates; and selecting one motion vector predictor from the list of candidates; wherein the deriving includes:
determining whether a reference picture for the current block is a long-term reference picture or a short-term reference picture, and whether a first reference picture for the neighboring block is a long-term reference picture or a short-term reference picture; andderiving the candidate from the first motion vector without scaling based on a temporal distance when each of the reference picture for the current block and the first reference picture for the neighboring block is determined to be a long-term reference picture, andderiving the candidate from the first motion vector by scaling based on a temporal distance when each of the reference picture for the current block and the first reference picture for the neighboring block is determined to be a short-term reference picture.