Orthogonal symmetric prefilter banks for discrete multiwavelet transforms

Traditional design of critically sampled prefilters for discrete multiwavelet transform ignores the preservation of the linear phase property, which is important for many applications, such as image coding and digital communications. Balanced multiwavelets solve this problem but make the filters longer. By using linear phase filter banks, we propose a simple algorithm for the design of orthogonal symmetric prefilter banks that can be used with the discrete multiwavelet transform. The prefilter bank resulted is orthogonal and critically sampled and can preserve the approximation power of the multiwavelet as well as the linear phase property. Experimental results show that the systems using the proposed symmetric prefilter banks give better performance as compared with using nonlinear phase prefilters.