A novel fractal watermarking technique

The paper describes a novel watermarking method to hide a binary watermark in image files compressed by fractal block coding. The watermarking method utilizes a special type of orthogonalization fractal coding method where the fractal affine transform is determined by range block mean and contrast scaling. Such orthogonalization fractal decoding has a unique mean-invariant property for each range block where the mean of a range block of the decoding series is invariant. The proposed watermark embedding procedure inserts an m-sequence into the quantized code of the range block means. The watermark detection is statistically determined by computing the correlation coefficient. Experimental results show that the watermark is robust against image processing operations such as JPEG compression, low-pass filtering, rescaling and clipping.