Novel robust image watermarking using difference correlation detector

This paper presents a robust digital image watermarking scheme based on subsampling and difference correlation. Four subimages are obtained from the host image by subsampling. A binary watermark is bit-wisely embedded in the DCT domain of two of the subimages selected by a secret key. The watermark is detected using coefficient difference correlation and does not need the original image. Since the subimages are highly correlated with each other, the proposed difference correlation detector has a better performance than a common coefficient correlation detection. Experimental results show good robustness of the proposed scheme.