Two-step Progressive Intra Prediction for Versatile Video Coding

In traditional intra prediction, the nearest reference samples are utilized to generate the prediction block. Although more directional intra modes and more reference lines have been proposed, the efficiency is still limited in predicting complex content with the local reference samples. To address this issue, a two-step progressive prediction method combining local and non-local information is proposed. The non-local information can be obtained through template matching based prediction, and the local information can be reconstructed by discarding low frequency coefficients. Experimental results show that the proposed method can achieve 0.87\% BD-rate reduction in VTM-7.0. In particular, the method is also of significant advantages over prediction schemes using only non-local information.