Image decoding method and image decoding apparatus for sample adaptive offset information
An image coding method includes performing: context arithmetic coding to consecutively code (i) first information indicating whether or not to perform SAO processing for a first region and (ii) second information indicating whether or not to use, in the SAO processing for the first region, information on SAO processing for a region except the first region; and bypass arithmetic coding to code other information after the first and second information are coded. The other information includes third information indicating whether the SAO processing is edge or band offset processing. In the performing of context arithmetic coding, an initial bit value in a bit string of a parameter indicating a type of the SAO processing is coded as the first information. In the performing of bypass arithmetic coding, a value of a next bit following the initial bit in the bit string of the parameter is coded as the third information.
1. An image decoding method for sample adaptive offset (SAO) information comprising:
performing decoding to consecutively decode (i) first information indicating whether or not to use, in the SAO processing for a first block of an image, information on the SAO processing for a second block which is different from the first block, (ii) a first bit of second information indicating whether or not to perform the SAO processing for the first block, and (iii) a second bit of the second information indicating whether the SAO processing for the first block is (a) edge offset processing performed according to an edge or (b) band offset processing performed according to a pixel value,
wherein the first information and the second information are included in SAO information related to the SAO processing for the first block,
wherein the performing decoding includes switching, while decoding the SAO information related to the SAO processing for the first block, between (i) context arithmetic decoding using variable probabilities and (ii) bypass arithmetic decoding using a fixed probability,
wherein (i) the first information and the first bit of the second information are decoded by the context arithmetic decoding and (ii) after the first information and the first bit of the second information are decoded by the context arithmetic decoding, the second bit of the second information is decoded by the bypass arithmetic decoding,
wherein the first bit of the second information is decoded by the context arithmetic decoding after the first information is decoded by the context arithmetic decoding,
wherein the performing decoding includes decoding other information, the other information is (i) information on the SAO processing for the first block, (ii) different from the first information and the second information, and (iii) decoded by the bypass arithmetic decoding, the other information including third information indicating an absolute value of an offset value, and
wherein when the SAO processing for the first block is the band offset processing, the other information includes (i) fourth information indicating whether the offset value is positive or negative and (ii) fifth information indicating a scope of application of the offset value.
2. An image decoding apparatus for sample adaptive offset (SAO) information comprising:
control circuitry; and
storage accessible from the control circuitry,
wherein the control circuitry performs decoding to consecutively decode (i) first information indicating whether or not to use, in the SAO processing for a first block of an image, information on the SAO processing for a second block which is different from the first block, (ii) a first bit of second information indicating whether or not to perform the SAO processing for the first block, and (iii) a second bit of the second information indicating whether the SAO processing for the first block is (a) edge offset processing performed according to an edge or (b) band offset processing performed according to a pixel value,
wherein the first information and the second information are included in SAO information related to the SAO processing for the first block,
wherein the decoding includes switching, while decoding the SAO information related to the SAO processing for the first block, between (i) context arithmetic decoding using variable probabilities and (ii) bypass arithmetic decoding using a fixed probability,
wherein (i) the first information and the first bit of the second information are decoded by the context arithmetic decoding and (ii) after the first information and the first bit of the second information are decoded by the context arithmetic decoding, the second bit of the second information is decoded by the bypass arithmetic decoding,
wherein the first bit of the second information is decoded by the context arithmetic decoding after the first information is decoded by the context arithmetic decoding,
wherein the decoding includes decoding other information, the other information is (i) information on the SAO processing for the first block, (ii) different from the first information and the second information, and (iii) decoded by the bypass arithmetic decoding, the other information including third information indicating an absolute value of an offset value, and
wherein when the SAO processing for the first block is the band offset processing, the other information includes (i) fourth information indicating whether the offset value is positive or negative and (ii) fifth information indicating a scope of application of the offset value.