An Improvement of the Watermark Detection in the Correlation-based Image Watermarking Methods

摘要

This paper aims to improve the accuracy of watermark detection in correlation-based watermarking methods for images. In the correlation-based watermarking method, watermark detection is carried out by computing the correlation between a watermarked image and a watermark code (pseudorandom sequence) to be checked for the presence. Hence its accuracy depends on the characteristics of watermark code and host images. In this paper, we first show an experimental result that a certain image may cause watermark detection errors. Then we develop an improved version of the watermark embedding process to be effective in such a situation. The improvement is accomplished by designing a whitening filter using a nonlinear programming algorithm. Numerical experiments show good performance as expected by us.