A Novel Algorithm for Watermarking and Image Encryption

Digital watermarking is a method of copyright protection of audio, images, video and text. We propose a new robust watermarking technique based on contourlet transform and singular value decomposition. The paper also proposes a novel encryption algorithm to store a signed double matrix as an RGB image. The entropy of the watermarked image and correlation coefficient of extracted watermark image is very close to ideal values, proving the correctness of proposed algorithm. Also experimental results show resiliency of the scheme against large blurring attack like mean and gaussian filtering, linear filtering (high pass and low pass filtering) , non-linear filtering (median filtering), addition of a constant offset to the pixel values and local exchange of pixels .Thus proving the security, effectiveness and robustness of the proposed watermarking algorithm.