A Genetic Algorithm based Steganography using Discrete Cosine Transformation (GASDCT)

摘要

In this paper a Genetic Algorithm based steganographic technique in frequency domain using discrete cosine transform has been proposed. A 2x2 sub mask of the source image is taken in row major order and Discrete Cosine Transformation is applied on it to generate four frequency components. Two bits of the authenticating image are embedded into each transformed coefficients except the first one. In each coefficient second and third positions from LSB are chosen for embedding in the transform domain. Stego sub intermediate image is generated through reverse transform. Sub mask from this intermediate image is taken as initial population. New Generation follqwed by Crossover is applied on initial population to enhance a layer of security. New Generation is applied to initial population. Rightmost three bits of each byte are taken, a consecutive bitwise XOR is applied on it in three steps which generates a triangular form. The first bit of each intermediate step is taken as the output and Crossover is performed on two consecutive pixels where two LSB bits of two consecutive bytes are swapped. The dimension of the hidden image is embedded followed by the content. Reverse process is followed during decoding. The proposed scheme obtains high image fidelity, PSNR and high capacity of embedding in stego images compared Chang Chin et al [1].