A semi-blind watermarking based on discrete wavelet transform

Abstract

This paper proposed a robust watermarking scheme based on discrete wavelet transform to hide a grayscale watermark in a digital image for image authentication. The proposed scheme employed toral automorphism to scramble the host image and the watermark so as to enhance the security and fidelity of the embedded watermark. Later, the permuted watermark and the permuted host image were transformed by discrete wavelet transform. Next, the transformed watermark was concealed in the low frequency coefficient of the transformed image by using the concept of codebook matching. Simulation results showed that the required extra storage of the proposed scheme for extracting the water-mark was lower than that of Lu et al.'s scheme. In addition, the extracted watermark image quality of the proposed methods was better than that of Shieh et al.'s scheme. According to the experimental results, the proposed scheme indeed outperformed Shieh et al.'s and Lu et al.'s schemes. Moreover, the proposed scheme was robust to various attacks, such as JPEG compression, Gaussian blurred, sharpening, cropping, brightness, contrast enhancement, rotation, and so on. © Springer-Verlag Berlin Heidelberg 2007.