A decoder is described, which receives an encoded data stream. The encoded data stream includes data representing a picture and a classification mode parameter. The classification mode parameter specifies a certain classification to be applied to samples in the picture, the certain classification selected from a plurality of classifications. The decoder decodes the encoded data stream to obtain a reconstructed picture and the classification mode parameter, classifies samples of the reconstructed picture into one of a plurality of classes using the certain classification specified by the classification mode parameter, and filters the samples of the reconstructed picture. A sample is filtered using a filter for the class into which the sample has been classified.