A method and image processing device are provided, including a deblocking filter. The deblocking filter modifies values of at most MA samples of the first image block as first filter output values, the at most MA samples being obtained from a column of the first image block that is perpendicular to and adjacent to the horizontal block edge; and modifies values of at most MB samples of the second image block as second filter output values, the at most MB samples being obtained from a column of the second image block that is perpendicular to and adjacent to the horizontal block edge. At most a number MA of sample values of the first image block adjacent to the block edge are modified and at most a number MB of sample values of the second image block adjacent to the block edge are modified, wherein MA