Discrete Cosine Transformation-Based Reversible Encoding

Abstract

This chapter deals with discrete cosine transformation (DCT)-based reversible encoding. At the beginning of the chapter, the generalized DCT is discussed along with its inverse transform pair. Sub-image (window)-based transform encoding with embedding and extraction process is given in detail based on 2 x 2 mask along with technical details of message encoding/decoding process. Various properties of DCT are also discussed. Computations of 2D and 3D DCT and IDCT with numerical examples are given to show the reversibility of transform pair with embedding and extraction algorithms in detail. A complete algorithm of implementation of steganographic scheme based on 2D DCT is also given along with results. Application of DCT is given at end.