在讨论最低有效位(LSB)算法特点及其抗几何攻击原理的基础上,提出一种新的抗几何攻击水印算法.首先对水印信息做适当的缩放以适应载体图像的大小,使水印和载体图像之间具有同步性；然后运用Logistic混沌系统对水印进行置乱,以增强算法的鲁棒性；最后从像素的低4位中随机选取嵌入位置通过逻辑运算嵌入水印.试验结果表明,算法能够很好地抵抗裁剪、旋转、缩放等几何攻击,对其他攻击同样具有一定的抵抗能力.%By analyzing the characteristics of least significant bits (LSB) and its theory against geometric attacks, a watermarking algorithm against geometric attacks was proposed. First, the watermark was appropriately zoomed to fit the size of the host image, so that the watermark has the synchronization with the host image. Then the watermark was scrambled by the Logistic chaotic system to enhance the robustness of the algorithm. Finally, the lower 4 bits were randomly selected from each pixel and the watermark was embedded by logic algorithm. The experimental results show that the algorithm has good resistance to crop, rotate, zoom and other geometric attacks, and it has some resistance to other attacks.
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