The fast development and the rapid spread of information technology have raised the issue of digitalimage copyright protection, which was mostly addressed through robust watermarking. To ensure the survival of the watermark after attacks, most works have been making use of an additional step at the embedding phase, and by so making the scheme unsuitable for real-time implementation. However, to be effective and secure, it is recommended to combine the watermarking algorithm and the capture sensor in one device. In this paper, we brought the extra stage to the detection side. We firstly studied the effect of some signal processing operations on a watermarked image, then we proposed a general model for watermark extraction whose parameters were determined using the artificial bee colony. The efficacy of the proposed method was validated by comparing its robustness with two state-of-art schemes focusing on the watermark extraction.
In an endeavor to deal with image copyright infringement, robust watermarking approaches are commonly used. However, most of the existing approaches either present a limited robustness or rely on highly computational algorithms, thereby limiting the efficiency of these solutions. In this paper, a novel blind and robust watermarking method is presented. First, the vertical and horizontal subbands coefficients, resulting from the wavelet transformation, are scrambled using a chaotic sequence and then gathered into individual blocks. Next, the mean value of each block is modulated according to watermark bit. At the extraction stage, based on the sign of the blocks’ mean, a blind watermark extractor is suggested. The imperceptibility, security, complexity, and robustness of the proposed approach have been evaluated and compared with state of the art solutions. Experimental results prove that the proposed approach successfully satisfies the watermarking requirement and outperforms existing methods against both geometric and signal processing attacks.
SummaryRobust watermarking provides valuable solutions to protect the copyright and secure digital images. In this paper, a robust and transparent watermarking scheme in the discrete cosine transform (DCT) domain is presented. The watermark is embedded into the difference of two adjacent DCT coefficients located at the same frequency. The embedding process involves optimal selection of adjacent blocks and DCT coefficients positions. For a given DCT block, the optimal selection is to find the coefficient with the lowest DCT frequency that requires the minimal variation to represent the target watermark bit. To insert the watermark, a new quantization index modulation (QIM) based method with irregular distance between continuous quantizers is employed. The performance of the proposed scheme was extensively evaluated using 12 benchmark images and a total of more than 90 attacks per image grouped into nine attack types including JPEG compression, filtering and noise contamination. Furthermore, robustness comparison with state‐of‐the‐art works was conducted, and the results demonstrate the superiority of the proposed scheme in terms of imperceptibility and robustness.
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