Low bit rate video encoder and decoder

A system for encoding a video signal into a bit stream, the video signal representative of a sequence of at least one video image frame, the system comprising:

• an image segmenter which segments the at least one video image frame into a plurality of objects;
• a feature extractor, coupled to the image segmenter, which forms at least one feature quantity for each of the objects;
• a first storage device which contains a set of generic objects;
• a classifier, coupled to the feature extractor and to the first storage device, which recognizes at least one of the objects as a corresponding generic object based upon the at least one feature quantity;
• a difference processor, coupled to the classifier, which computes a difference signal in dependence upon a difference between the at least one of the objects and the corresponding generic object, the difference processor including a second storage device in which a representation of the difference signal is stored;
• a motion estimator which provides a motion compensation signal based upon the motion of at least one of the objects from a first frame to a second frame;
• and
• a multiplexer which provides the bit stream based upon the symbolic code, the difference signal, and the motion compensation signal.

A method of encoding a video signal representative of a sequence of at least one video image frame into a bit stream, the method comprising the steps of:

• assigning a symbolic code to an object contained in the at least one video frame, wherein the symbolic code identifies a corresponding generic object from a set of generic objects;
• computing a difference signal in dependence upon a difference between the object and the corresponding generic object;
• and
• multiplexing the difference signal and the symbolic code to form the bit stream.

A method of reconstructing a video image from a bit stream representative of an encoded video signal, the method comprising the steps of:

• extracting a symbolic code from the encoded video signal, wherein the symbolic code identifies a corresponding generic object from a set of generic objects;
• extracting a difference signal from the encoded video signal, wherein the difference signal is representative of a difference between an object and the corresponding generic object;
• modifying the corresponding generic object in dependence upon the difference signal;
• and
• generating the modified corresponding generic object.