| 主权项 |
1. An image decoding apparatus that decodes encoded data representing an encoded picture that is split using a coding tree unit including coding units hierarchically defined in a tree structure, as a unit, wherein the coding unit includes a transform tree including transform units hierarchically defined in a tree structure, and the encoded data includes a coded block flag indicating whether each of the transform units includes a non-zero value, the image decoding apparatus comprising:
a decoding unit configured to decode the coded block flag; a holding unit configured to hold a value of the coded block flag corresponding to each of the transform units; and a flag-value updating unit configured to update the value of the coded block flag held by the holding unit, which initializes the value of the coded block flag held by the holding unit to a predetermined initial value (indicating zero at a lower level) before processing is performed on the coding tree unit; updates, in a case where a value of the coded block flag for a target transform unit, decoded by the decoding unit is different from the predetermined initial value, among the coded block flags held by the holding unit, the value of the coded block flag for the target transform unit, and the value of the coded block flag for a transform unit at a level below the transform unit, to the value of the coded block flag decoded by the decoding unit; and uses, in a case where the value of the coded block flag for the target transform unit, decoded by the decoding unit is equal to the predetermined initial value, among the coded block flags held by the holding unit, the value of the coded block flag for the target transform unit, and the value of the coded block flag for a transform unit in a layer below the transform unit, as the value of the coded block flag encoded by the decoding unit. |
