Abstract: A scrambling method wherein each image line (23-309) of a frame having been produced in unscrambled form before being scrambled, is given the pseudorandomly determined address (B) of the memory line in the storage memory (8) in which said image line is to be stored on reception; and wherein the moment (or the running order) for broadcasting said image line is determined so that on reception, the image line causes, because it is stored in the memory line to which it was addressed, the image line previously stored at the same address to be output to the television set at the right moment (or in the right order) so that an unscrambled picture is reconstructed.