On optimal wavelet transform for watermarking

In this paper, we propose a method of improving imperceptibility and robustness of a wavelet-based watermark by finding the optimal wavelet transform used for image decomposition required for watermark embedding. Our approach can be easily generalized for enhancing watermarking performance of any wavelet-based technique as they usually use predefined (not necessarily optimal) wavelets. We measured imperceptibility by PSNR and considered robustness to filtering or JPEG compression. To find the optimal wavelet, we used both local and global (genetic algorithm) optimizers. We applied our method to a recent wavelet-based watermarking scheme and achieved better watermarking properties both in terms of imperceptibility and robustness.