US Patent 7283588 Deblocking filter

A method in video decoding for reducing blocking artifacts between a first and a second block in a block wise coded video picture by performing a test on pixel lines crossing a boundary and/or an extension of the boundary between the first and the second block and executing a de-blocking filter operation on boundary neighboring pixels if the test indicates artifacts. The method further includes performing the test on a subset of the pixel lines only, and if the test indicates artifacts, executing a de-blocking filter operation on the boundary neighboring pixels in each of the pixel lines crossing the boundary.