Method for encoding and decoding images based on constrained offset compensation and loop filter, and apparatus therefor
Provided are a method and apparatus for encoding and decoding images based on constrained offset compensation and a loop filter. The image decoding apparatus: receives, from an encoder, a first indicator indicating whether a sequence, a picture, a frame, a slice, a coding unit (CU), a prediction unit (PU), and/or a transform unit (TU) supports constrained offset compensation; receives, from the encoder, a second indicator indicating whether constrained sample adaptive offset (SAO) compensation or an adaptive loop filter (ALF) is applied; receives a parameter from the encoder; and applies the SAO compensation or the ALF to pixels of a restored image on the basis of the second indicator and the parameter.
1. An apparatus for decoding a video, the apparatus comprising:
a decoder to decode:
a constrained offset compensation indicator indicating whether at least one of a picture, a tile, and a coding unit (CU) supports constrained offset compensation,
a sample adaptive offset (SAO) compensation indicator indicating whether to perform SAO compensation, and decode an SAO parameter; and
a filter unit to perform SAO compensation on a target sample within a target block of a reconstructed video based on the SAO compensation indicator and the SAO parameter, wherein the filter unit determines an offset category for the SAO compensation based on the constrained offset compensation indicator and encoding parameters of the target block of SAO compensation and at least one of neighboring blocks of the target block when an edge offset is applied to the offset compensation target sample within the target block,
wherein the SAO parameter comprises at least one of an offset type, an offset category information, an offset value and an offset sign, wherein the offset type specifies whether the edge offset is applied to the offset compensation target sample or a band offset is applied to the offset compensation target sample and the offset category information specifies the offsets classified according to locations of two neighboring samples of the offset compensation target sample.
2. The apparatus of claim 1 , wherein the offset category information is determined by comparing values of the offset compensation target sample and two neighboring samples of the offset compensation target sample when the edge offset is applied to the offset compensation target sample.