In one embodiment, the apparatus includes a decoder. The decoder is configured to obtain at least three horizontally successive reference pixel values including a pixel to be filtered, and apply first weight factors to at least each of the three horizontally successive reference pixel values. The first weight factors are different according to pixel position. A first filtered value is obtained by the decoder by summing at least the three weighted horizontally successive pixel values. The decoder is also configured to obtain at least three vertically successive reference pixel values including a pixel to be filtered, and apply second weight factors to at least each of the three vertically successive reference pixel values. The second weight factors are different according to pixel position. A second filtered value is obtained by the decoder by summing at least the three weighted vertically successive pixel values.