A Novel Digital Watermark Detecting Scheme Based on Principal Components

摘要

Digital watermarking technique provides an effective way to protect the image. A detecting scheme for digital image watermarking, which using principal components of the watermarked image, was proposed in this paper. The scheme was based on DWT and DCT, and using principal components of the watermarked image at the same time, As we know that the principal components of an image has the virtue of insensitivity to geometrical transform, filtering and rotating operation, so using this character for watermark detecting should have the same merit. The course of the scheme is as follow: first, the original image was decomposed by 2-D discrete wavelet transform and the detail sub-bands are reserved, then the approximation image is transformed by discrete cosine transform and embedded with watermark image. At the stage of watermark detection, The DWT and DCT were carried out first, at the same domain we extract the embedded watermark, which was corrupted by attacks. Then applied principal components transform to the corrupted image to restore the watermark. After processing, the restored watermark had least mean square error with the original watermark image. The experimental results showed its good unification between the robustness and insensitivity, and the quality of detected watermark is improved greatly at the same time.