Watermarking of Images in Discrete Cosine transform

Data embedding is simplest technique to achieve the secret data sharing information. Now days a color image is a very popular to consider cover image medium used to send the secret data. I have proposed an approach for hiding a secret image in a cover image. In the beginning, the DCT [8] of image is computed that is compress the secret image, and then encrypt cover data by DES. Various authors have proposed many watermarking algorithms. These algorithms are implemented in ether the spatial, frequency or wavelet domains. But which algorithms are better? Is embedding a watermark in one domain better than another? Do combining domains result in a better watermarking algorithm? This report attempts to answer these questions by selecting eight algorithms and analyzing them. Of these eight algorithms 2 embeds the watermark in the spatial domain, 2 in the frequency domain, 2 in the wavelet domain, one in a combination of frequency and spatial domain. Do to the wide variety of algorithms a standard benchmark is also developed, within this report, to analyze the algorithms. In this work, the steganographic paradigm of data hiding in digital images has implemented. Several algorithms based on this approach exist in literature and the strengths and limitations of these algorithms are mentioned. Two existing algorithms which secures a cover image during embedding and DCT [9] algorithm embeds secrete image into a cover image while inherently preserving the first order statistics of the image. Finally, embed the cover image into the middle-frequency domain of DCT [1]. After embedding the secret image, the goal of steganography can be successfully achieved .The proposed algorithms are successful in embedding the image in bit alteration .The purpose of this project is provide n-Bit security.