Abstract: A method and apparatus for reducing the output bit rate in a video object planes sequence encoder. An approximation of the shape of an object on a current frame is generated and used, along with a predicted image of the object from a subsequent frame and an estimate of the displacement of the object, to predict an image of the object in a current frame. A stripe is formed around the predicted image and the picture elements contained in the stripe are assigned texture values. The predicted image and stripe are subtracted from the current frame to form an error signal which is masked by the approximate shape of the object and provided to an entropy coder for transmission at an output bit rate.

Abstract: A video signal encoder operable for distinguishing between errors resulting from a change in a video signal input to the encoder and errors resulting from ineffective quantization includes a quantized section and an unquantized section, with each section having a separate image predictor. A switch mechanism selectively provides each image predictor with a corresponding signal having a portion containing video data derived from a prior frame for use in predicting an image represented on a subsequent video frame. The signals are also provided to an image analysis unit for measuring motion of the image and for adjusting a quantization step size of a quantizer when quantization errors are detected.