In this paper, a 2D discrete W transform is turned to another 2D discrete transform.The kernel of the resulting transform is separable, thus it can be computed by the wellknown row-column algorithm. Therefore, a fast algorithm is obtained for 2D DWT witharbitrary length. Methods are also given in the paper for computing 2D cyclic convolutions,2D skew-cyclic convolutions and 2D generalized discrete Fourier transforms by 2D discreteW transform. Furthermore, running time of the algorithms on a kind of micro computeris given.