Generalized polyphase structure-based Mth-band filter design and application to image interpolation

A generalized polyphase (GP) structure-based method for the design of linear-phase Mth-band FIR filters satisfying the time-domain interpolation condition is presented. Some new transform matrices that allow for the use of an arbitrary number of branches in the GP structure are developed. Closed-form frequency specifications for constituent filters of the GP realization are obtained, making an independent and fast design of the short-length constituent filters possible. The proposed GP-based method is then extended for the design of a class of interpolation filters with certain regularities. Some of the interpolation filters designed based on the proposed GP structure are also applied to image resizing. Simulation results show that our interpolation filter gives a superior resized image than the common cubic spline interpolation does.