A Practical Multipurpose Color Image Watermarking Algorithm for Copyright Protection and Image Authentication

A multipurpose color image watermarking algorithm for copyright protection and image authentication is proposed. The basic idea is to embed the fragile and robust watermarks into different color components of the color image simultaneously. Based on some techniques in cryptology, lossless compression and the method of Least Significant Bit (LSB), the fragile watermark is embedded in spatial domain to achieve the goal of image authentication and watermark extracting control. By modifying the Discrete Cosine Transform (DCT) coefficients, the robust watermark is embedded in the frequency domain to obtain the aim of copyright protection. Simulation results show that the fragile watermark has a good prompting performance upon the tampering of the image and the robust watermark has a strong robustness to JPEG, filtering, brightness and contrast enhancement and additive Gaussian noise.