To solve the problem of watermark embedding and extracting of quantum color images, a method of using novel enhanced quantum representation and Gray-code scrambling was proposed. For the embedding proc-ess of quantum watermarking, at first, the position and color of pixels in watermark image were scrambled by the controlled-not gates, and then, the scrambled watermark with 2n×2n image size and 24 color qubits (8 qubits per channel) was expanded to an image with 2n+1×2n+2 image size and 3 color qubits (1 qubit per channel). Finally, the color value of the expanded watermark image was added to the lowest qubit of color value of the carrier im-age sized 2n+1×2n+2 by modulo 2 additions. The watermark was extracted from the watermarked image by apply-ing operations in the reverse order. The experimental results show that the proposed method is superior to the contrast method in terms of four items: visual quality, robustness performance under noises, scrambling effect of watermark image, and computational complexity.%为解决量子彩色图像的水印嵌入和抽取问题,提出一种采用新颖的增强量子图像描述和格雷码置乱的实现方案.对于嵌入过程,首先采用受控非门对于水印图像像素的位置和颜色同时置乱;然后将置乱后水印图像的幅度从2n×2n扩展到2n+1×2n+2,将像素颜色值由24比特(每通道8比特)改为3比特(每通道1比特);最后将扩展后水印图像的颜色值,通过模2加运算嵌入到幅度为2n+1×2n+2载体图像颜色值的最低位中.抽取过程为嵌入的逆过程.仿真结果表明,该方案在可视化质量、噪声下的鲁棒性能、水印图像置乱效果和计算复杂度4个方面优于对比方案.
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