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

An image decoding method for decoding a coded image on a block-by-block basis, the method comprising:

• calculating a disparity motion vector predictor for predicting a motion vector of a current block to be decoded, from a motion vector of a disparity block that is a block having a relationship of disparity with the current block and located at a position corresponding to a position of the current block;
• decoding (i) identification information corresponding to a motion vector predictor selected in coding from among one or more motion vector predictor candidates including the disparity motion vector predictor and (ii) a motion vector difference that is a difference between the motion vector of the current block and the motion vector predictor;
• and
• selecting the motion vector predictor from among the one or more motion vector predictor candidates, using the identification information corresponding to the motion vector predictor.

An image coding apparatus for coding an image on a block-by-block basis, the apparatus comprising:

• a calculating unit configured to calculate a disparity motion vector predictor for predicting a motion vector of a current block to be coded, from a motion vector of a disparity block that is a block having a relationship of disparity with the current block and located at a position corresponding to a position of the current block;
• a selecting unit configured to select a motion vector predictor for use in prediction of the motion vector of the current block, from among one or more motion vector predictor candidates including the disparity motion vector predictor;
• and
• a coding unit configured to code (i) identification information corresponding to the motion vector predictor selected from among the one or more motion vector predictor candidates and (ii) a motion vector difference that is a difference between the motion vector of the current block and the motion vector predictor.

An image decoding apparatus for decoding a coded image on a block-by-block basis, the apparatus comprising:

• a calculating unit configured to calculate a disparity motion vector predictor for predicting a motion vector of a current block to be decoded, from a motion vector of a disparity block that is a block having a relationship of disparity with the current block and located at a position corresponding to a position of the current block;
• a decoding unit configured to decode (i) identification information corresponding to the motion vector predictor selected in coding from among one or more motion vector predictor candidates including the disparity motion vector predictor and (ii) a motion vector difference that is a difference between the motion vector of the current block and the motion vector predictor;
• and
• a selecting unit configured to select the motion vector predictor from among the one or more motion vector predictor candidates, using the identification information corresponding to the motion vector predictor.