A video decoding method includes extracting offset mergence information of a current largest coding unit (LCU), the offset mergence information indicating whether to adopt a second offset parameter as a first offset parameter of the current LCU; reconstructing the first offset parameter of the current LCU based on the offset mergence information, the first offset parameter including an offset type, an offset value, and an offset class of the current LCU; determining whether the current LCU is an edge type or a band type, based on the offset type; determining an edge direction according to the edge type or a band range according to the band type, based on the offset class; determining a difference value between reconstructed pixels and original pixels included in the offset class, based on the offset value; and adjusting pixel values of reconstructed pixels based on the difference value.