Method and apparatus of adaptive loop filtering

摘要

In a block-based motion compensated system, coding noises may arise due to lossy operations such as quantization. Deblocking is often used to alleviate visibility of coding artifacts by applying filtering across block boundaries adaptively. In the recent HEVC development, adaptive loop filtering (ALF) is being adopted to process deblocked reconstruction frames. Adaptive loop filtering is applied to reconstructed video data across multiple frames to reduce visibility of coding artifacts in the temporal domain. In a HEVC system, conventional ALF can be selectively turned ON or OFF for each block in a frame or a slice. The advanced ALF disclosed here allows a choice of multiple filter sets that can be applied to the reconstructed video data adaptively. Furthermore, the advanced ALF adopts a new unit for the filtering process to apply so that more flexible and/or localized processing can be provided. Furthermore, the advanced ALF allows a decoder to derive respective information for applying the filtering process without side information.

主权项

1. A method for processing video using one adaptive processing selected from adaptive loop filter (ALF), adaptive offset (AO) and adaptive clipping (AC), wherein a picture is partitioned into coding units for applying coding process to each coding unit, the method comprising:
receiving input data to said one adaptive processing selected from the ALF, the AO and the AC, wherein the input data corresponds to reconstructed or reconstructed-and-deblocked coding units of the picture; dividing the input data into multiple filter units, wherein at least one filter unit includes two or more boundary-aligned reconstructed or reconstructed-and-deblocked coding units; selecting a candidate filter from a candidate filter set for said one adaptive processing selected from the ALF, the AO and the AC, wherein the candidate filter set consists of at least two candidate filters for the ALF or at least two candidate filters for the AO and the AC; applying said one adaptive processing selected from the ALF, the AO and the AC using the candidate filter to each filter unit to generate each processed filter unit by using the candidate filter selected to all boundary-aligned reconstructed or reconstructed-and-deblocked coding units in each filter unit; and providing processed video data consisting of the processed filter units.