Non blind digital watermarking technique using DCT and Cross chaos map

Digital watermarking is the process of embedding secret information into a digital signal which may be used to verify its authenticity or the identity of its owners. In this paper, a non-blind digital image watermarking algorithm based on Discrete cosine transform, Cross chaotic map and Arnold transform has been described. Initially, Arnold´s transformation is applied on the watermark signal. Then, Cross chaos sequence is applied on this encrypted watermark to encrypt further. Discrete cosine transformation is applied to the cover image to transform the signal from the spatial domain to the frequency domain, where the watermark signal is embedded. It is a kind of non-blind scheme as the extraction needs the original image. Peak signal to noise ratio (PSNR) is used to evaluate the algorithm. The quality of the extracted watermark is evaluated using term Normalized cross-correlation (NC). From the results, it may be concluded that our algorithm is resistant enough against the common attacks.