Abstract: Taking advantages of the multiresolution feature of wavelet transform and the property of human visual system, a multi-Signature watermarking algorithm for color image is presented here. With this algorithm, the multi-signature watermarks are mixed with the chaotic sequences and spread over the different wavelet domains of RGB color spaces of the image. The watermarked image is obtained by using the inverse wavelet transform. Multi-watermarking system can be a valid way of ownership identification, and can achieve good transparency and robustness. Experimental results and analysis are given to demonstrate that the proposed algorithm is extremely robust to common image processing such as noise addition, cropping, median filtering, and JPEG compression. Moreover, if the watermarked color image is converted into the gray image, the signature watermarks can still be detected.