摘要
数字水印图像的鲁棒性和稳定性与打印/扫描过程中的失真密切相关。打印是数字图像向半色调图像转换的过程,会对水印图像造成低通滤波攻击、半色调攻击和几何攻击;扫描是打印的逆过程,是半色调图像向数字图像转换的过程,会对水印图像引入低通滤波攻击和几何攻击。低通滤波攻击和半色调攻击会对数字水印图像造成非线性像素值失真,几何攻击则会引起几何失真。非线性像素值失真的校正对策有:对打印机或扫描仪的分辨率进行最优化设置,对gamma值进行校正,使用空间低通滤波去除高斯噪声等;几何失真的校正对策有:通过周期性的冗余嵌入克服几何异步攻击,进行模版嵌入设计实现同步等。
The robustness and stability of digital watermarking image is closely related to the distortion caused by the print-scan process. Printing is the conversion process between digital images and halftone images, and causes low-pass filtering attack, halftone attack and geometric attack into the watermarking image; scanning is the reverse process of printing, which leads into low pass filtering attack and geometric attack. Thereinto, nonlinear distortion of pixel values on digital watermarking image is caused by low pass filtering attack and halftone attack, while geometric attack causes the geometric distortion. The correction countermeasures for the nonlinear distortion of pixel value include optimally setting the resolution of printer or scanner, correcting the gamma value, using the sl^atial low-pass filter to remove Gauss noise, etc while the reductive countermeasures for geometric distortion consists of overcoming geometric asynchronous attacks by embedding the cyclical redundancy, designing template embedding to achieve synchronization, and so on.
出处
《包装学报》
2013年第2期40-44,共5页
Packaging Journal
基金
国家自然科学基金资助项目(61170101)
关键词
打印
扫描
数字水印
非线性像素值失真
几何失真
失真还原
print-scan
digital watermarking
nonlinear distortion of pixel values
geometric distortion
reductive countermeasures for distortion
