1. A method of representing motion in a sequence of digitized images comprising generating and coding a plurality of versions of a motion vector field at different resolutions, comprising the steps of: producing a motion vector field at a first, coarse, resolution and at a second, finer, resolution; up-sampling the coarse resolution version of the motion vector field; comparing the up-sampled coarse resolution version of the motion vector field with the finer resolution version of the motion vector field; coding the coarse resolution version of the motion vector field; and coding the finer resolution version of the motion vector field on the basis of the results of the comparison.