Dual Digital Watermarking for Rightful Ownership and Tamper Localization using Stationary Wavelet Transform
The applications of digital watermarking are gradually rising from ownership identification to recovery of tarnished portion of digital image. This paper proposes a dual digital watermarking algorithm where a robust and a fragile watermarks are inserted into standard and medical images separately to provide rightful ownership and to localize the invisible tampered portions of the image respectively. The redundant coefficients produced by stationary wavelet transform help to increase watermark holding capacity of host image without any deterioration in imperceptibility and robustness of the watermark. The robust watermark is embedded in the green plane and the fragile watermark in the blue plane of the host image. This scheme achieves significantly high robustness while maintaining comparably better imperceptibility than other state of the art similar kinds of works. The tamper localization is achieved through splitting the blue plane of the image and the fragile watermark into four equal portions and embedding them correspondingly. This helps to determine the location of the tampers in one or multiple portions of the image.