Fast and efficient prediction unit size selection for HEVC intra prediction

In this paper, a fast learning-based Coding Unit (CU) size selection method is presented for High Efficiency Video Coding (HEVC) intra prediction. Our analysis shows that non-normalized histogram of oriented gradient (n-HOG) can be used to select CU size. For each size of CU, n-HOGs of training sequences are clustered to construct a codebook offline. The optimum CU sizes are determined by comparing its n-HOG with the codebook. Experimental results show that the fast intra prediction CU selection scheme speeds up intra coding significantly with negligible increment of Bjontegaard Delta rate.