1. A data encoding system including an encoder for receiving input data and generating corresponding encoded output data, the encoder including digital processing means for processing said input data to generate for each input therein a plurality of corresponding data layers including at least one basic layer and at least one enhancement layer, and encoding means for receiving said data layers and generating therefrom the encoded output data, said encoding means further comprising block selecting means for selecting one or more sub-regions of said at least one enhancement layer and modelling said one or more sub-regions for representation thereof in the output data by way of descriptive model parameters.