Patent ID: 9516333
Filing Date: 2016-12-06
CPC Classification: H04N

Claim Text:
1. An arithmetic decoding device which decodes coded data of each transform coefficient which is obtained by performing frequency transform on a target image for each unit domain and each transform coefficient obtained through a transform skip or a transform/quantization bypass, the device comprising: a context index deriving circuit that derives a context index of a nonzero transform coefficient presence/absence flag indicating whether or not the transform coefficient is 0 in a unit domain; and a syntax decoding circuit that arithmetically decodes the non-zero transform coefficient presence/absence flag by referring to the derived context index, wherein the context index deriving circuit derives a context index common to non-zero coefficient presence/absence flags corresponding to transform coefficients obtained through the transform skip or the transform/quantization bypass, wherein the context index deriving circuit derives separate context indexes for (i) a case where the transform skip flag is 1 or the transform/quantization bypass flag is 1, and (ii) a case where the transform skip flag is 0 and the transform/quantization bypass flag is 0.