EFFICIENT ROUNDING FOR DEBLOCKING

摘要

The present disclosure relates to deblocking filtering which is applicable to smoothing the block boundaries in an image or video coding and decoding. In particular, the deblocking filtering is either strong or weak, wherein the clipping is performed differently in the strong filtering and the weak filtering.

主权项

1. An image encoding and decoding apparatus for encoding an image and decoding the encoded image on a per block basis, the image encoding and decoding apparatus comprising:
an encoding unit configured to encode the image on a per block basis to generate the encoded image; a reconstruction unit configured to decode the encoded image to generate a reconstructed image; a judging unit configured to judge whether a strong or a weak filter is to be applied to a boundary between a current block included in the reconstructed image and a neighboring block adjacent to the current block; a calculating unit configured to calculate a linear combination of current samples in the current block and adjacent samples in the neighboring block, the current samples and the adjacent samples forming a line of samples; a shifting unit configured to shift the linear combination right by a predetermined number of bits; a clipping unit configured to clip the shifted linear combination to generate a filtered sample of the filtered current block; and a filtering unit configured to filter three samples included in each of the current block and the neighboring block when the strong filter is to be applied, and filter one or two samples included in each of the current block and the neighboring block when the weak filter is to be applied, wherein the clipping by the clipping unit for the strong filter is controlled by a first clipping parameter and the clipping by the clipping unit for the weak filter is always controlled by a second clipping parameter regardless of any other condition, the first clipping parameter and the second clipping parameter depending on a strength of the boundary but having a different value with each other.