| 摘要 |
Method and apparatus are disclosed for producing an encoded symbol stream to provide a compressed representation of an image frame. Each pixel is encoded by generating a predicted value p(x, y) of the actual pixel value c(x, y), based on stored previously reconstructed values, r, of other pixels in the frame. The predicted value may be calculated using DPCM. The predicted value is constrained to lie within a prediction range u to 1. A test range a to b encapsulates the predicted value but lies within the prediction range. The 'position' of the test range relative to the prediction range and the actual value is determined and used to (1) provide at least one encoded data symbol of the encoded symbol stream, and (2) refine both the reconstructed value r(x, y) associated with the pixel and the prediction range upper and lower limits, u and 1, for use in future iterations of the method. The reconstructed image improves with each iteration (compare Figures 8a and 8b). A corresponding decoding method is also disclosed. The invention may be implemented in a video recorder. |
