A Discrete Wavelet Transform based Adaptive Steganography for Digital Images

Steganography is the scheme of surreptitious communication by hiding the data inside data with the aim of concealing the presence of secret data from inquisitive eyes. Pervasiveness as well as availability of redundant information in an image makes it the alluring carrier medium. However, all parts of an image cannot be used evenly to hide the secret information. In this paper, an approach for image steganography has been made through a method that exploits standard deviation of high frequency components of the carrier image to identify the potential region for secret embedding. Discrete Wavelet Transform (DWT) is used to segregate high frequency and low frequency components of the image. The secret embedding is done in three higher frequency components with non-uniform high embedding efficiency method. The block having standard deviation lower than the mean value is embedded with relatively higher efficiency compared to the blocks with higher standard deviation. Secret image is encrypted using a chaotic mapping which creates diffusion and thus is safe even in the situation where an adversary have the knowledge of embedding technique used. The experimental results for the method were observed with acceptable cover-stego structural similarity, stego image fidelity, embedding efficiency and statistical imperceptibility.