Distance-based weighted prediction for H.264 intra coding

Intra 4times4 is one of the two primary intra prediction types supported in H.264/AVC. For intra 4times4 prediction, eight modes are to capture orientations of images with DC mode to reflect flat regions. Therefore the smoothly-varying regions which are very common in ordinary images can not be well decorrelated. In this paper, to improve decorrelation performance of intra 4times4 prediction, we propose a distance-based weighted prediction (DWP) method to take the place of DC mode. In DWP, weighted prediction is performed with the weighting coefficients inversely relative to the distances between current pixel and its reference pixels. We also present an integral DWP (iDWP) method which is of much lower computational complexity than DWP. Experimental results demonstrate that DWP and iDWP yield average PSNR enhancements of 0.12 dB and 0.1 dB over current H.264 using 4times4 DC prediction respectively.