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 decoding method for decoding an encoded image on a per block basis, the image decoding method comprising:
decoding the encoded image to generate a reconstructed image; judging 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; calculating 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; shifting the linear combination right by a predetermined number of bits; clipping the shifted linear combination to generate a filtered sample of the filtered current block; and filtering three samples included in each of the current block and the neighboring block when the strong filter is to be applied, and filtering 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 for the strong filter is controlled by a first clipping parameter and the clipping 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.