Mirroring of coefficients for Transform Skipping in Video Coding

Abstract

This paper studies the Transform Skip option of the emerging High Efficiency Video Coding (HEVC) standard, and presents a modification to the ordering of coefficients within a transform skipped residual block. Depending on the scanning order for the given block, the coefficients are rearranged relative to their original spatial positions. The rearrangement is achieved by mirroring the coefficients across one of the block diagonals. When the diagonal scan is used, mirroring across the antidiagonal is used, otherwise mirroring across the main diagonal (transpose) is used. In this way the distribution of significant coefficients is closer to the distribution in a case when transform is applied. Therefore the entropy coding may benefit from the new arrangement. The experiments show BD-rate gains of up to 2.4% for Screen Content sequences.

Implicit Seleted Transform Skip Method For Avs3

“…Reverse scanning method [9] [10] change the coefficients scanning order, reverse scanning order is more adaptive to the coefficient coding of intra-coded blocks. Mirroring reordering [11] is a method similar to the Reverse scanning method, that the new scanning order is mirrored from the previous order. Moreover, the mode-dependent reordering method [12] is proposed to improve the coding performance as well.…”