A visual quality assessment method and system are based on deriving a quality metric by comparing sub-band approximations of a distorted image and an undistorted version of the same image, providing a good compromise between computational complexity and accuracy. Preferably, each of the arms carries a third fastener or connecting eye intermediate the first and second fasteners. Each of the first tooth and the second tooth include an inner end adjacent the yoke and an outer end opposite the inner end. The predistorted fragments are then separately processed and recombined to arrive at the system output signal.