Stable watermarking technique based on XNOR operation and scale relationship

Abstract

Digital watermark technique is often used to solve these problems and protect the copyright of multimedia transferred over the Internet. Most watermark methods use pixel values or coefficients as the judgment condition to embed or extract a watermark image. The variation of these values may lead to the inaccurate condition such that an incorrect judgment has been laid out. To avoid this problem, we design a stable judgment mechanism, in which the outcome will not be seriously influenced by the variation. The principle of judgment depends on the scale relationship of two pixels. From the observation of common signal processing operations, we can find that the pixel value of processed image usually keeps stable unless an image has been manipulated by cropping attack or halftone transformation. In the watermark embedding process, we use the XNOR operation to record the outcome to form a secret key instead of modifying pixel values. This can greatly help reduce the modification strength from image processing operations. Experiment results show that the proposed method can resist various attacks and keep the image quality friendly.