Position dependent linear intra prediction for image coding
Intra prediction has been efficiently employed in block based image/video coding to remove the spatial redundancy. In this paper, we propose a position dependent linear intra prediction (PDLIP) approach to further improve the accuracy of prediction. Specifically, for each prediction direction, the prediction of each sample within a target block is calculated as a linear weighted summation of the surrounding spatial neighboring samples in a fixed window. And the prediction coefficients are adaptively derived in the encoding process using the least square estimation method. The derivation process utilizes the original data of the previous image with the same prediction direction after rate-distortion selection to adaptively adjust to the video contents and local context within one block. To alleviate the computation burden of decoding, these prediction coefficients are sent to decoder as side information. Experimental results demonstrate that the proposed PDLIP can achieve a significant coding gain with a slight increase in computational complexity at encoder.