混沌映射的半脆弱图像数字水印算法

Chaos Based Semi-Fragile Image Watermarking Algorithm

提出了一种抗JPEG有损压缩的半脆弱图像数字水印算法．该算法充分利用混沌映射对初值的敏感性,并根据JPEG图像压缩过程中DCT系数的不变特性,将预先量化的DCT低频系数和水印密钥合成为混沌系统的初值,经过多次混沌迭代生成水印信号．根据水印信号调整块对间DCT系数的大小,完成水印的嵌入调制．实验结果表明,该算法对JPEG有损压缩具有良好的鲁棒性,同时可对图像内容的恶意篡改进行精确的检测与定位．

A semi-fragile image watermarking technique that accepts JPEG lossy compression was developed. With the high sensitivity on initial value of chaotic mapping and the invariant properties of DCT coefficients before and after JPEG compression, the pre-quantized low DCW coefficients and a watermarking key are combined as the initial value of logistic map for generating the watermark. The watermarked image was obtained by modifying the DCT coefficients in block pairs according to the watermark. The experimental results showed the effectiveness of this system. The proposed technique was robust against JPEG lossy compression, but sensitive to the malicious attacks on the watermarked image. In the meantime, it can localize the tampers correctly and accurately.