On the design of finite wordlength IIR filters for video applications

The problem of designing finite precision one-dimensional infinite impulse response (IIR) digital filters for video processing is addressed. The design algorithm is based on simultaneous minimization of magnitude, phase, and stability errors in a discrete space of solutions using simulated annealing. It is demonstrated that the approach results in filters characterized by a substantially reduced nonlinearity of the phase response in filter passband, which is critical in any video processing application. To reduce image degradations due to ripples of the filter step response, another error term is introduced into the cost function. It is demonstrated that this additional term permits significant reduction of step response overshoots, and thus the visibility of degradations in a filtered image. The designed IIR filters are compared with their finite impulse response (FIR) counterparts in terms of characteristic parameters as well as distortion visibility in processed images