Abstract: An image decoding method decodes a coded stream which includes plural processing units and a header of the processing units, and which is generated by coding a moving picture using inter prediction, the processing units including at least one processing unit divided in a hierarchy, the hierarchy including: a highest hierarchical layer in which a coding unit exists as a largest processing unit; and a lower hierarchical layer in which a prediction unit exists. The method comprises: identifying, by parsing hierarchy depth information stored in the header and indicating a hierarchical layer higher than a lowest hierarchical layer in which a smallest prediction unit exits, a hierarchical layer which is indicated by the hierarchy depth information or a hierarchical layer higher than the indicated hierarchical layer, the hierarchical layer having a prediction unit in which a reference index is stored; and decoding the prediction unit, using the reference index.

Abstract: An image coding method decodes a coded stream which is generated by inter prediction coding a moving picture and includes processing units and a header of such units, the processing units including at least one processing unit divided in a hierarchy, the hierarchy including: a highest hierarchical layer in which a coding unit is a largest processing unit; and a lower hierarchical layer in which a prediction unit exists. The method comprises: identifying, by parsing hierarchy depth information stored in the header and indicating a hierarchical layer higher than a lowest hierarchical layer in which a smallest prediction unit exits, a hierarchical layer which is indicated by the hierarchy depth information or a hierarchical layer higher than the indicated hierarchical layer, the hierarchical layer having a prediction unit that stores an adaptive motion vector resolution switch flag necessary for decoding; and decoding the prediction unit, using the flag.

Abstract: An image decoding method which can improve both image quality and coding efficiency is an image decoding method for decoding a coded stream which includes a plurality of processing units and a header for the processing units, the coded stream being generated by coding a moving picture, the processing units including at least one processing unit layered to be split into a plurality of smaller processing units, the image decoding method including specifying a hierarchical layer having a processing unit in which a parameter necessary for decoding is stored, by parsing hierarchy depth information stored in the header, and decoding the processing unit using the parameter stored in the processing unit located at the specified hierarchical layer.

Abstract: A moving picture decoding method according to the present invention includes: performing intra prediction on a target block to calculate values of predicted samples of the target block; and calculating reconstructed samples of the target block by adding difference data and the values of the predicted samples of the target block, wherein in the performing of intra prediction, validity of each of reference samples that are located one of immediately above and immediately to the left of the target block is determined, and when the reference samples include both a valid reference sample and an invalid reference sample, the intra prediction is performed using the valid reference sample, and an intra-predicted reference sample is determined as a valid reference sample, and an inter-predicted reference sample is determined as an invalid reference sample.