a texture the process performed in block 52 could be the process reserved for flat zones in block 20 generally a noise reduction by averaging calculated on the pixels in the kernel a singular pixel could indeed be a pixel distorted by noise however the abovementioned criterion particularly its third or fourth component also enables pixels located on a transition between zones of different brightness to be detected which would also be detected in block 16 as belonging to a texture such a detection in block 16 is not necessarily wrong since a transition between two texture elements can be considered to belong to the texture however better results have been obtained by processing such pixels using directional averaging fig6 shows an example of using the pixels in the reference kernel to perform a simple directional averaging calculation in the reference kernel nine pixels are kept the central pixel and the north n south s east e west w north west nw north east ne south west sw and south east se pixels i e a reduced reference kernel of 3 u00d7 3 pixels is formed the sum of the differences is calculated for each pair of opposite pixels in the reduced kernel i e d 11 d 14 or d w d e d 1 d 24 or d nw d se d 3 d 22 or d n d s and d 5 d 20 or d ne d sw the outgoing pixel px out is then calculated as the mean of the pixels corresponding to the minimum sum of the differences for example if the minimum sum is d n d s the following is obtained.