Patent Document ID: 8942493
Application ID: 13504250
Patent Flag: 1

Claim One:
1. An image decoding method for decoding coded image data, said image decoding method comprising: determining (i) a low-order context which is a context associated with a type of a single quantization coefficient to be decoded of the coded image data and (ii) a high-order context that is common to the low-order context and a context associated with another type; calculating decoding probability information to be used in arithmetic decoding of the single quantization coefficient to be decoded, using (i) high-order probability information corresponding to the determined high-order context and (ii) low-order probability information corresponding to the determined low-order context; performing the arithmetic decoding on each binary symbol of the single quantization coefficient to be decoded, using (i) the high-order probability information corresponding to the determined high-order context and (ii) the low-order probability information corresponding to the determined low-order context, to generate a binary signal; performing multi-value conversion of the binary signal to reconstruct image data; and updating the high-order probability information and the low-order probability information based on the binary symbol.