Variable Rate Steganography in Gray Scale Digital Images Using Neighborhood Pixel Information

Steganography is the art of hiding the fact that communication is taking place, by hiding information in otherinformation. Security has always been a major concern since time immemorial. In the past, people used hidden tattoos orinvisible ink to convey steganographic content. Today, digital technology and Internet provide for easy to use cover media forsteganography. In order to improve the security by providing the stego image with imperceptible quality, three differentsteganographic methods for gray level images are presented in this paper. Four neighbors, diagonal neighbors and eightneighbors methods are employed in our scheme. These methods utilize a pixel’s dependency on its neighborhood and psychovisual redundancy to ascertain the smooth areas and complicated areas in the image. In smooth areas we embed three bits ofsecret information. In the complicated areas, variable rate bits are embedded. From the experimental results it is seen that theproposed methods achieve a much higher visual quality as indicated by the high peak signal-to-noise ratio in spite of hiding alarger number of secret bits in the image. In addition, to embed this large amount of secret information, at most only half ofthe total number of pixels in an image is used. Moreover, extraction of the secret information is independent of original coverimage