Abstract
In recent years, many works on digital image watermarking have been proposed all aiming at protection of the copyright of an image document or authentication of data. In this paper, to serve the purpose of copyright protection and integrity verification of image, an improved distortion-compensated quantization index modulation image watermarking algorithm is presented based on quantization index modulation(QIM) and contourlet transform technology. Since human visual system is less sensitive to the image edges, watermarking is applied in the contourlet domain, which represents image edges sparsely. Its improved robustness is due to embedding in the directional sub-band with the highest energy and optimal control of its quantization scalar factor. With blind detection in mind, in the proposed watermark decoding scheme, the bit error probability of proposed method is analytically calculated and verified by simulation. Results of performed experiments demonstrate that the proposed method is robust against JPEG compression, additive white Gaussian noise (AWGN), Median filtering and scaling attack, etc.
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