Two Stage Color Image Steganography using DCT (TSCIS-DCT)

Abstract

In frequency domain steganography, use of color images for secret data hiding may prove to be a decisive innovation. The proposed concept uses two color images for hiding a color/gray authenticating message/image. The mathematical technique of Discrete Cosine Transform (DCT) is applied on each block of size 2x2 taken in row major order from three color planes (Red, Green & Blue) sequentially and from two carrier images alternatively. A single secret message/image bit is fabricated within the transformed real frequency component of each source image byte except the first frequency component of each mask. The first frequency component of each block is used for re-adjustment to maintain the quantum value positive, non-fractional in spatial domain and also to reduce the integrated noise due to embedding. The pseudorandom position of embedding and subsequent extraction is generated by a logical expression. Experimental results of this technique reveal more efficiency compared to other similar technique. © 2013 Springer-Verlag.