Patent ID: 7283588
Filing Date: 2007-10-16
Classification: H04N

Abstract:
1. 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 first test of adjacent blocks and a second test of 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, performing the second test on a subset S of the pixel lines only, and if the test indicates artifacts, executing the de-blocking filter operation on the boundary neighboring pixels in each of the pixel lines crossing the boundary, wherein performing the second test on said subset of pixel lines only includes testing the following relation for said subset of pixel lines: wherein a is the third closest pixel on the left hand side of the boundary and/or the extension of the boundary, b is the second closest pixel on the left hand side of the boundary and/or the extension of the boundary, c is the closest pixel on the left hand side of the boundary and/or an extension of the boundary, d is the closest pixel on the right hand side of the boundary and/or an extension of the boundary, e is the second closest pixel on the right hand side of the boundary and/or an extension of the boundary and f is the third closest pixel on the right hand side of the boundary and/or an extension of the boundary, i is the line number of lines in the subset S and β′(QP) is a threshold value dependent on a first quantization parameter for the video coding, if the relation is true, executing the following re-calculation operation of the neighboring pixels on each of the pixel lines crossing the boundary: clipping within a value range (−γ, γ), wherein γ is a second quantization parameter found in a second look-up table dependent on the first quantization parameter and a strength value for the boundary, wherein b′, c′, d′ and e′ are re-calculated values of corresponding original pixels values.