Image encoding device, image decoding device and program

An image decoding device comprising:

• a cross-component predictor configured to generate a predicted block of a second component through cross-component prediction in which a block of the second component is predicted by referring to decoded pixels of a first component and decoded pixels of the second component;
• a candidate generator configured to generate candidates for a transform type to be applied to inverse transform processing on transform coefficients of the second component, the transform coefficients corresponding to prediction residuals that represent errors between the predicted block of the second component and the block of the second component;
• and
• an inverse transformer configured to perform the inverse transform processing on the transform coefficients of the second component by using a transform type selected from among the candidates generated by the candidate generator,
• wherein the candidate generator is configured to generate the candidates for the transform type, based on a mode indicating a type of a process of the cross-component prediction.

An image decoding method performed at an image decoding device, comprising:

• generating a predicted block of a second component through cross-component prediction in which a block of the second component is predicted by referring to decoded pixels of a first component and decoded pixels of the second component;
• generating candidates for a transform type to be applied to inverse transform processing on transform coefficients of the second component, the transform coefficients corresponding to prediction residuals that represent errors between the predicted block of the second component and the block of the second component;
• and
• performing the inverse transform processing on the transform coefficients of the second component by using a transform type selected from among the generated candidates,
• wherein the generating the candidates comprises generating the candidates for the transform type, based on a mode indicating a type of a process of the cross-component prediction.