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The ability against the collage attack of semi-fragile watermarking is improved by embedding the watermark of a block in other blocks, but the tamper detection performance is impaired under general tampering. A two-stage detection method is proposed to improve the tamper detection performance of semi-fragile watermarking. For each 8 × 8 block, six-bit(More)
To improve the imperceptibility, security and tamper detection performance, a self-embedding watermarking scheme against JPEG compression is proposed in this work. The recovery watermark of all blocks in the host image, which consists of 6-bit DC-code and 5-bit AC-code and simultaneously used to both tamper detection and tamper recovery, is recombined based(More)
To meet different security demands, this work proposes an alterable-capacity algorithm for JPEG images. First, the original image is divided into 8×8 blocks. The authentication watermarks of each block are computed by its quantized DCT coefficients and the secret-matrix generated by user key, where the size of secret-matrix depends on the watermark(More)
A semi-fragile watermarking scheme is proposed to discriminate general tampering and collage attack in this paper. Five bits watermark data of each block generated are divided into the general tampering watermark (GTW) and collage attack watermark (CAW), which are embedded in the same block and the other blocks to discriminate general tampering and collage(More)
For lower sampling rate and better imaging quality, a compressive adaptive ghost imaging is proposed by adopting the sharing mechanism and fellow relationship in the wavelet tree. The sharing mechanisms, including intrascale and interscale sharing mechanisms, and fellow relationship are excavated from the wavelet tree and utilized for sampling. The shared(More)
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