A Robust Blind Algorithm for Color Image Watermarking

This paper presents a novel algorithm for the digital watermarking of still color images based on Fourier transform (FFT) and log-polar mapping (LPM). The host color image is first transformed to a gray image, whose Fourier domain is then mapped to a log-polar system. The watermark is finally embedded into this system´s Fourier domain. During extraction, the color image is first transformed to a gray image with the aid of a template for error correction. Then the corresponding inverse transforms are performed to obtain the magnitude spectrum and the watermark is recovered by a local maximum method. Our experimental results demonstrated that the proposed scheme is robust to various geometric transformations and JPEG compression.