Image coding apparatus, method for coding image, program therefor, image decoding apparatus, method for decoding image, and program therefor
AssigneeCanon Kabushiki Kaisha
InventorMasaaki Kobayashi
Life of this patent
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Abstract
An image coding method for dividing an input image into a plurality of divisional blocks having different sizes, and coding the image for each of the divisional blocks includes acquiring attribute information of a target block, setting a control parameter for controlling an image quality of the target block, determining a prediction control parameter based on the attribute information, calculating a difference value between the control parameter and the prediction control parameter, and coding the calculated difference value.
Claims20
An image coding apparatus for dividing an image into a plurality of blocks and coding the image for each of the blocks, the image coding apparatus comprising:
- a quantization parameter determination unit configured to determine a first quantization parameter to be used for quantization of a first block;
- a prediction mode determination unit configured to determine, in a case where the first block is coded with intra-prediction, an intra-prediction mode in the intra-prediction for the first block;
- a block determination unit configured to determine at least one second block for coding information indicating the first quantization parameter from blocks in an area different from the first block, on the basis of the intra-prediction mode for the first block;
- and
- a coding unit configured to code, as the information, a difference value between the first quantization parameter and a quantization parameter of the at least one second block or a value based on the quantization parameter of the at least one second block.
An image decoding apparatus for decoding coded data generated by coding individual blocks of an image, the image decoding apparatus comprising:
- a decoding unit configured to decode, from the coded data, a difference value regarding a first quantization parameter used for inverse quantization of a first block;
- a deriving unit configured to derive, in a case where the first block is decoded with intra-prediction, information indicating an intra-prediction mode in the intra-prediction for the first block from the coded data;
- a determination unit configured to determine at least one second block for deriving the first quantization parameter from blocks in an area different from the first block on the basis of the intra-prediction mode for the first block;
- and
- a calculation unit configured to calculate the first quantization parameter on the basis of the difference value regarding the first quantization parameter and a quantization parameter of the at least one second block or a value based on the quantization parameter of the at least one second block.
An image coding method for dividing an image into a plurality of blocks and coding the image for each of the blocks, the image coding method comprising:
- determining a first quantization parameter to be used for quantization of a first block;
- determining, in a case where the first block is coded with intra-prediction, an intra-prediction mode in the intra-prediction for the first block;
- determining at least one second block for coding information indicating the first quantization parameter from blocks in an area different from the first block, on the basis of the intra-prediction mode for the first block;
- and
- coding, as the information, a difference value between the first quantization parameter and a quantization parameter of the at least one second block or a value based on the quantization parameter of the at least one second block.
An image decoding method for decoding coded data generated by coding individual blocks of an image, the image decoding method comprising:
- decoding, from the coded data, a difference value regarding a first quantization parameter used for inverse quantization of a first block;
- deriving, in a case where the first block is decoded with intra-prediction, information indicating an intra-prediction mode in the intra-prediction for the first block from the coded data;
- determining at least one second block for deriving the first quantization parameter from blocks in an area different from the first block on the basis of the intra-prediction mode for the first block;
- and
- calculating the first quantization parameter on the basis of the difference value regarding the first quantization parameter and a quantization parameter of the at least one second block or a value based on the quantization parameter of the at least one second block.
A non-transitory computer readable storage medium for storing a computer program for executing an image coding method for dividing an image into a plurality of blocks and coding the image for each of the blocks, the image coding method comprising:
- determining a first quantization parameter to be used for quantization of a first block;
- determining, in a case where the first block is coded with intra-prediction, an intra-prediction mode in the intra-prediction for the first block;
- determining at least one second block for coding information indicating the first quantization parameter from blocks in an area different from the first block, on the basis of the intra-prediction mode for the first block;
- and
- coding, as the information, a difference value between the first quantization parameter and a quantization parameter of the at least one second block or a value based on the quantization parameter of the at least one second block.
A non-transitory computer readable storage medium for storing a computer program for executing an image decoding method for decoding coded data generated by coding individual blocks of an image, the image decoding method comprising:
- decoding, from the coded data, a difference value regarding a first quantization parameter used for inverse quantization of a first block;
- deriving, in a case where the first block is decoded with intra-prediction, information indicating an intra-prediction mode in the intra-prediction for the first block from the coded data;
- determining at least one second block for deriving the first quantization parameter from blocks in an area different from the first block on the basis of the intra-prediction mode for the first block;
- and
- calculating the first quantization parameter on the basis of the difference value regarding the first quantization parameter and a quantization parameter of the at least one second block or a value based on the quantization parameter of the at least one second block.
Dependencies are inferred from the claim text.