High precision edge prediction for intra coding

In the current video coding standard H.264/AVC, eight directional intra prediction modes are defined to predict edges in a block by using the already coded surrounding reference pixels. The H.264/AVC intra prediction scheme offers a limited set of prediction directions. Therefore, edges of certain directions cannot be accurately predicted. In the case of sharp edges, the inaccurate prediction leads to high frequency coefficients in the prediction error, that are expensive to code. To improve the prediction of edges, a new edge prediction method is introduced. This method detects the presence of an edge in the surrounding blocks and uses an extension of it along its exact direction for the prediction. Since this proposed method allows prediction in any direction without any additional overhead, bitrate reductions of 8% for sequences containing a lot of edges are achieved.