| 摘要 |
PROBLEM TO BE SOLVED: To reduce electric power consumption occurring during encoding without greatly reducing encoding efficiency.SOLUTION: An image encoding apparatus derives a color difference in a pixel of a prediction block as a reference color difference block from a reference color difference sample indicating the color difference of pixel necessary for an inter-coding in accordance with a color difference intra-prediction mode. The difference between the reference color difference block and the color difference sample of inputted encoded block is derived as a color difference predictive residual, and an evaluation value of the color difference predictive residual (color difference component evaluation value=ISCb[i] + ISCr[i]) is derived. Such a processing is used for the candidate of color difference intra-prediction mode applicable in spite of the luminance intra-prediction mode. When the evaluation value of a color difference predictive residual component is equal to or less than a threshold value ThC, the color difference intra-prediction mode corresponding to the evaluation value of color difference predictive residual component is applied as a color difference intra-prediction mode for the prediction block. |
