1. An apparatus, comprising: an encoder for encoding a picture, in which the encoder filters at least one reference picture to obtain at least one filtered reference picture, and predictively encodes the picture using the at least one filtered reference picture wherein at least one set of parametric filters used for the filtering is pre-defined before encoding the picture or a video sequence to which the picture belongs and said pre-defined set is estimated based on an expected mismatch between the picture and the at least one reference picture, and wherein coefficients of the at least one pre-defined set of parametric filters are calculated based on estimating a group of filters which compensate for the expected mismatch and classifying at least a portion of the estimated group of filters.