Trailing artifact avoidance for low bit-rate block-based video coders

A method is provided to avoid or otherwise reduce luminance and/or chrominance trailing artifacts in block-based hybrid video coders. The proposed trailing artifact avoidance approach has at its core three main components. The first component is a method to identify flat blocks in the source frame where the appearance of trailing artifacts would be very noticeable, and where flatness is determined according to several proposed criteria. The second component is a method to identify bad blocks, which refer to predicted blocks in motion estimation that correspond to flat blocks in the source frame and that contain trailing artifacts. The third component is a high performance motion estimation approach to avoid trailing artifacts when they are detected within a bad block. Experimental results using an H.264 based-coder indicate the proposed method is very effective in reducing or eliminating the appearance of trailing artifacts.