Apparatus and method of sample adaptive offset for luma and chroma components

Abstract

A method and apparatus for processing reconstructed video using in-loop filter in a video coding system are disclosed. The method uses chroma in-loop filter indication to indicate whether chroma components are processed by in-loop filter when the luma in-loop filter indication indicates that in-loop filter processing is applied to the luma component. An additional flag may be used to indicate whether the in-loop filter processing is applied to an entire picture using same in-loop filter information or each block of the picture using individual in-loop filter information. Various embodiments according to the present invention to increase efficiency are disclosed, wherein various aspects of in-loop filter information are taken into consideration for efficient coding such as the property of quadtree-based partition, boundary conditions of a block, in-loop filter information sharing between luma and chroma components, indexing to a set of in-loop filter information, and prediction of in-loop filter information.

1 . A method for processing reconstructed video using in-loop filter in a video decoder, wherein a picture area of the reconstructed video is partitioned into blocks and the in-loop filter is applied to the blocks, the method comprising:
 deriving reconstructed video data comprising reconstructed block;   determining if a current reconstructed block is a new partition based on a merge flag;   receiving in-loop filter information responsive to the current reconstructed block being a new partition;   deriving the in-loop filter information from a target block responsive to the current reconstructed block not being said new partition, wherein the current reconstructed block is merged with the target block selected from two candidate blocks corresponding to two neighboring blocks of the current reconstructed block, and the target block is selected from said two neighboring blocks according to a second flag; and   applying in-loop filter processing to the current reconstructed block using the in-loop filter information.   
     
     
         2 . The method of  claim 1 , wherein deriving the in-loop filter information is performed based on said merge flag responsive to an existence of more than one neighboring block; and
 wherein said deriving the in-loop filter information is inferred responsive to an existence of only one neighboring block.   
     
     
         3 . The method of  claim 1 , further comprising: applying quadtree-based partitioning to the picture area, wherein said quadtree-based partitioning comprises recursively partitioning a region into four sub-regions until a smallest unit is reached. 
     
     
         4 . The method of  claim 3 , wherein the smallest unit comprises a largest coding unit (LCU). 
     
     
         5 . The method of  claim 3 , wherein at least one of said one or more candidate blocks is eliminated from merging with the current reconstructed block according to a quadtree-partition property and merging information of said one or more candidate blocks. 
     
     
         6 . An apparatus for processing reconstructed video using in-loop filter in a video decoder, wherein a picture area of the reconstructed video is partitioned into blocks and the in-loop filter is applied to the blocks, the apparatus comprising processing circuitry configured to:
 derive reconstructed video data comprising reconstructed block;   determine if a current reconstructed block is a new partition based on a merge flag;   receive in-loop filter information responsive to the current reconstructed block being a new partition;   derive the in-loop filter information from a target block responsive to the current reconstructed block not being said new partition, wherein the current reconstructed block is merged with the target block selected from two candidate blocks corresponding to two neighboring blocks of the current reconstructed block, and the target block is selected from said two neighboring blocks according to a second flag; and   apply in-loop filter processing to the current reconstructed block using the in-loop filter information.