Image decoding method and image coding method

Abstract

An image decoding method is an image decoding method of decoding coded image data, including selecting, based on a type of a decoding target signal, an arithmetic decoding method that is used to decode the decoding target signal, from among a plurality of arithmetic decoding methods that include: a first arithmetic decoding method which is performed based on a symbol occurrence probability obtained according to a context, and which involves update of the symbol occurrence probability according to a decoding symbol; and a second arithmetic decoding method which is performed based on a symbol occurrence probability obtained according to a context, and which maintains the symbol occurrence probability that is other than 50%.

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