Targeted watermark removal of a SVD-based image watermarking scheme

Digital watermarking is widely used to verify the authenticity or integrity of multimedia contents, such as images and videos. In the last few years, a well-known numerical tool called singular value decomposition (SVD) has received much attention from the watermarking community. Designers of SVD-based schemes usually use dewatermarking tools such as Stirmark to prove the robustness of their schemes. Although, these tools are valuable but their attacks usually reduce the quality of watermarked images. On the other hand, there is another group of attacks in which the attacker needs to know the watermarking algorithm to perform the attack. In this paper, an attack in this group has been designed to remove the watermark from a specific SVD-based watermarking scheme [1]. The attack tries to change the exact space where watermark has been embedded. The experiments show our attack makes fewer changes to remove embedded watermark than other distortions available in Stirmark, so the quality of attacked image is better than processed image by using Stirmark in terms of PSNR.