Method of removing deblocking artifacts

A method of removing blocking artifacts by a decoding apparatus, the method comprising:

• determining, by the decoding apparatus, a boundary strength for only each of every 4-sample edge in a coding unit which lies on grid lines of an 8×8 sample grid and is an edge of a prediction unit or a transform unit;
• determining, by the decoding apparatus, whether or not deblocking filtering is performed on the 4-sample edge if the boundary strength for the 4-sample edge is not equal to zero, wherein the boundary strength for the 4-sample edge is determined based on two blocks immediately adjacent to and located on either side of the 4-sample edge;
• selecting, by the decoding apparatus, a deblocking filter to be applied among a strong filter and a weak filter if the deblocking filtering is performed on the 4-sample edge;
• filtering, by the decoding apparatus, the 4-sample edge using the selected deblocking filter, and
• wherein the boundary strength is set equal to 0, 1 or 2.