Two-dimensional filter banks containing prefilter

Two-dimensional (2D) filter banks are used in subband coding of images, and are systems which split a signal into the narrow bands and/or resynthesize it. This paper presents a method of constructing 2D filter banks using 2D prefilter and 2D polyphase filter banks. First, the input signal is divided into four kinds of band on the 2D plane by 2D prefilter with IFIR (Interpolated FIR) transfer function. Then the 2D prefilter is designed so that the four kinds of band become 1. These resulting output signals are band-split separately and synthesized by 2D DFT polyphase filter banks. Hence, its design method becomes very simple and both the required order and the number of multiplications can be reduced.