2-DIMENSIONAL PERIODICALLY SHIFT VARIANT DIGITAL-FILTERS

Two-dimensional (2-D) periodically shift variant (PSV) digital filters are considered. These filters have potential applications in processi ng video signals with cyclostationary noise, scrambling of digital ima ges, and in 2-D multirate signal processing. The filters are formulate d in the form of the Fornasini-Marchesini (FM) state-space model with periodic coefficients. This PSV model is then represented as a new shi ft-invariant system which is named the ''Kiok-Neon'' model. This model has several advantages that include ease of analysis and reduced comp utations compared to the existing state-space models. An algorithm is developed that transforms any given 2-D PSV FM system to its equivalen t ''Kiok-Neon'' model. Invertibility of this model is an important con sideration, especially in image scrambling applications. A condition i s established for the invertibility of the ''Kiok-Neon'' model of the 2-D PSV system. Also, the inverse system can be easily computed from t he original. It is established that the 2-D PSV system is asymptotical ly stable if an equivalent shift-invariant FM system is asymptotically stable. The established results are illustrated with examples.