Image scrambling using 2-D periodically shift variant filters
Kyung Sub Joo, Tamal Bose · 2002
Two-dimensional (2-D) periodically shift variant (PSV) digital filters are considered for image scrambling applications. The filters are formulated in the form of a difference equation and a Fornasini-Marchesini (FM) state-space model with periodic coefficients. These PSV models are then represented as shift-invariant systems which are named block difference equation and "Kiok-Neon" model respectively. Invertibility of this model is an important consideration, especially in image scrambling applications. A condition is established for the invertibility of the "Kiok-Neon" model of the 2-D PSV system. Also, the inverse system can be easily computed from the original system.