Evaluation of Copyright Marking Systems
ICMCS '99 Proceedings of the IEEE International Conference on Multimedia Computing and Systems - Volume 2
IEEE Transactions on Image Processing
Capacity of full frame DCT image watermarks
IEEE Transactions on Image Processing
A mathematical analysis of the DCT coefficient distributions for images
IEEE Transactions on Image Processing
Content-Adaptive Robust Image Watermarking with Posterior HMM-Based Detector
IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences
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In this paper, we propose a DCT-based blind watermarking system, with detection performed in a two-step algorithm. In embedding, each bit is inserted in a PN spreading pattern in 12 positions of DCT coefficients of an 8×8 block. The watermark gain, α, is optimized in robustness and invisibility. In detection process, a preliminary decision is obtained by correlation matching and then verified by choosing the more similar spreading pattern with the restored one. Most of bit errors are corrected in verificiation process. The poposed method has been tested for several test images, with attacks including lowpass/median filtering and JPEG compression, but excluding geometrical RST attacks. After verificiation, BER reduces to 0.5% with no attack. Even under heavey JPEG compression, BER stays lower than 9%. Compared with other methods, the proposed method is better in watermark detection and far exceeds others in watermark size.