Efficient image tamper detection and recovery technique using dual watermark

In this paper, we proposed an efficient dual watermark scheme for image tamper detection and recovery. In the proposed watermarking algorithm each block in the image contains watermark of other two blocks, i.e. two copies of watermark of the whole image is maintained and second chance for block recovery is provided in case one copy is destroyed. The algorithm proposed by Lee and Shinfeng is unable to detect the tamper in the watermarked image, if any one bit or more than one bit in 5-MSBs (most significant bits) is changed. In this paper we demonstrated the attacks and concluded that there is a flaw in their watermarking technique and the attacker can tamper a watermarked image easily without being detected and results are compared. Experimental results show that our proposed dual watermark technique is efficient.