A method and apparatus for deblocking process using multiple processing units are disclosed. The video image is divided into at least two regions. The in-loop filter is applied to block boundaries associated with said at least two regions using multiple processing units. The in-loop filter is re-applied to one or more second block boundaries adjacent to region edge between two regions after applying the in-loop filter to the first block boundaries adjacent to the region edge. Furthermore, at least a first portion of said applying the in-loop filter to the first block boundaries and a second portion of said applying the in-loop filter to the second block boundaries are performed concurrently. The multiple processing units may correspond to multiple processing cores within one processor chip.