1. An apparatus for encoding a moving image including a human face comprising: means for receiving video input data; means for output of data representing one frame of the image; identification means arranged in operation for each frame of the image to identify that part of the input data corresponding to the mouth of the face represented and (a) in a first phase of operation to compare the mouth data parts of each frame with those of other frames to select a representative set of mouth data parts, to store the selected parts and to output the selected parts; (b) in a second phase to compare the mouth data part of each frame with those of the stored set and to generate a codeword indicating which member of the set the mouth data part of that frame most closely resembles.