Bitstream decoder

A method of decoding in a decoder a bitstream representing an image, where the bitstream comprises a plurality of blocks of residual samples, where a block of reconstructed image samples is obtained by adding a block of residual samples to a block of predictions, the predictions being formed by applying a selected prediction process to reference samples in the reconstructed image, the method comprising:

• receiving the bitstream;
• for each block, forming predictions and adding a respective prediction to each residual sample to form a reconstructed image sample;
• providing a reconstructed image from the reconstructed image samples;
• and
• outputting the reconstructed image;
• wherein forming predictions for a block comprises:
• determining reference samples for said block;
• applying a first directional or non-directional prediction mode to the reference samples to form at least a first set of one or more predictions for said block;
• and
• applying one or more subsequent, different, directional or non-directional prediction modes to the reference samples to form at least one subsequent set of one or more predictions for said block, where any subsequent directional prediction mode differs from any first directional prediction mode in a spatial direction of prediction;