Patent ID: 6864813

Claim:
An arithmetic decoding method in which arithmetic decoding is performed in pipeline processing on arithmetic coded data obtained by performing arithmetic coding on orthogonal transformation coefficients of multi-valued data, the method comprising: determining whether input arithmetic coded data belongs to a more probable symbol or a less probable symbol on a number line that is divided using a probability estimation value of the more probable symbol and a probability estimation value of the less probable symbol, and outputting, as a decoded symbol, a predicted value of a symbol to which the arithmetic coded data belongs; assigning a context, using a context model formed to be common to a DC component and an AC component, to each node of a context tree constructed corresponding to a decision sequence having tree-structured decision events to perform binary decomposition on the orthogonal transformation coefficients in performing arithmetic coding, transiting on the context tree corresponding to a value of the decoded symbol whenever the decoded symbol is generated, and extracting a context assigned to the node of a transition destination; and estimating a probability estimation value of a less probable symbol, a predicted value of a more probable symbol or the less probable symbol corresponding to the output context to provide to the determining.