Intra prediction image generation device using cross-component liner model, image decoding apparatus, and image coding apparatus using same
An intra prediction image decoding apparatus is provided with a prediction parameter derivation circuitry that derives prediction parameters of multiple luminance blocks. A Cross-component Linear Model (CCLM) is used to specify the model and the prediction parameter is obtained, and thus an intra prediction image with reference to the prediction parameters is generated.
1. An intra prediction image generation device for generating an intra prediction image, the intra prediction image generation device comprising:
prediction parameter derivation circuitry that decodes a Cross-Component Linear Model (CCLM) index and derives prediction parameters of a current block when a cross-component linear model is applied; and
prediction image generation circuitry that generates the intra prediction image by using the prediction parameters, a sample value of a luma component and a shift value,
wherein:
the prediction parameter derivation circuitry specifies one of three cross-component linear models by using the CCLM index,
in a case that a top CCLM model of the three cross-component linear models is specified, the prediction parameter derivation circuitry derives the prediction parameters by using at least neighboring top luma pixel values and neighboring top chroma pixel values,
in a case that a left CCLM model of the three cross-component linear models is specified, the prediction parameter derivation circuitry derives the prediction parameters by using at least neighboring left luma pixel values and neighboring left chroma pixel values, and
in a case that a combining CCLM model of the three cross-component linear models is specified, the prediction parameter derivation circuitry derives the prediction parameters by using at least one of neighboring top luma pixel values, neighboring top chroma pixel values, neighboring left luma pixel values and neighboring left chroma pixel values.
2. An image decoding apparatus comprising the intra prediction image generation device according to claim 1 .
3. An image coding apparatus comprising the intra prediction image generation device according to claim 1 .
4. The intra prediction image generation device according to claim 1 , wherein
in the case that the top CCLM model of the three cross-component linear models is specified,
the prediction parameters are derived by using a number of pixels on a top neighboring region of the current block.
5. The intra prediction image generation device according to claim 1 , wherein
in the case that the left CCLM model of the three cross-component linear models is specified,
the prediction parameters are derived by using a number of pixels on a left neighboring region of the current block.
6. The intra prediction image generation device according to claim 1 , wherein
in the case that the combining CCLM model of the three cross-component linear models is specified,
the prediction parameters are derived by using a number of pixels on a top neighboring region and a number of pixels on a left neighboring region.