An effiient and well-structured algorithm is presented for the computation of all four types of the radix -2 discrete W transform （DWT）. The computational requirements for the type I of the dis-crete W transform （DWT-I

also called the discrete Hartley transform

DHT）are N/2（log

N-3）+2 multiplications and N/2（3 log2N-5）+6 additions. That is more efficient than other any existing algorithm for the DWT-I or DHT.