The application of two-dimensional finite-precision IIR filters to enhanced NTSC coding

Abstract

The goal of this paper is to study the application of two-dimensional (2-D) finite-precision infinite impulse response (IIR) filters to enhanced National Television System Committee (NTSC) coding. It is well-known that suitable twoor three-dimensional (3-D) digital filtering greatly improves the quality of NTSC pictures by suppressing the interference between the luminance Y and the chrominances I, Q. Thus far, 2-D and 3-D finite impulse response (FIR) filters have been used to reduce or eliminate these cross effects. To achieve good performance, however, they require many coefficients. Since, in general, IIR filters need fewer coefficients to approximate a given magnitude response, we investigate the possibility of applying 2-D IIR filters to the NTSC encoding/decoding. We also study the feasibility of using digital filters for NTSC channel filtering; this would permit a digital-only encoder. To design suitable filters, we use a method based on multiple constraint optimization and simulated annealing. We propose a new implementation structure for the IIR filters that differs from the zero-phase FIR structure. We simulate the full NTSC coding chain and compare the resulting images for both filter types.