Intra prediction image generation device using cross-component liner model, image decoding apparatus, and image coding apparatus using same

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.