IMAGE ENCODER, IMAGE ENCODING METHOD, IMAGE ENCODING PROGRAM, TRANSMITTER, TRANSMISSION METHOD AND TRANSMISSION PROGRAM

摘要

PROBLEM TO BE SOLVED: To solve a problem such that it takes much time for arithmetic encoding processing for changing a context with peripheral encoding information.SOLUTION: An image encoder divides a difference coefficient being a transfer coefficient of a differential signal between an image of an encoding object and a prediction image, and encodes the difference coefficient in a partial region unit. A significant sub-block information encoding control section 708 and an arithmetic encoding section 701 encode significant sub-block information showing that significant difference coefficient information showing that a difference coefficient value is not zero and is significant exists in the partial region of the encoding object. A context index processing section 711 calculates a peripheral significant index for determining a context index for encoding the significant sub-block information and a context index for encoding the significant difference coefficient information. A significant coefficient information encoding control section 706 and the arithmetic encoding section 701 encode the significant difference coefficient information for each difference coefficient in the partial region of the encoding object.