CODER/DECODER FOR TELEVISION IMAGE SUB-BAND COMPATIBLE CODING, AND ITS APPLICATION TO HIERARCHICAL MOTION CODING BY TREE STRUCTURES

A coder/decoder including a device for constructing from the preceding decoded image and from the current source image two pyramids of images of unlike resolution. Each pyramid contains the same number of images ordered identically according to their resolution. Each image corresponds to a level of resolution which is half as large in the horizontal and vertical directions of the image as a preceding level of resolution. Each pyramid is applied to a first and second serial input of the hierarchical motion estimator which outputs a motion vector having a magnitude which is proportional to the estimated motion between the two pyramids.