数字图像水印技术中滤波新方法

New filtering method in digital image watermarking technology

针对数字图像发生了旋转和其它变化时,一些滤波方法不能对图像中的数字水印进行识别的问题,基于对数极坐标映射(LPM),提出了一种数字图像水印滤波的新方法。为检测新设计的滤波方法的实用价值,进行了不同滤波器的数字图像水印识别能力的比较。结果表明:当含数字水印的图像发生小旋转和缩小变化,即:旋转10度和缩小为原图像的0.9倍时,纯相位滤波器(POF)不能对图像中的数字水印进行识别,但新设计的滤波器能对图像中数字水印具有较好的识别能力;当含数字水印的图像旋转45度、缩小为原图像的0.7倍以及旋转和缩小同时发生时,新设计的滤波器对图像变化后的数字水印仍有较好的识别能力。结果证明:这种新的滤波方法对数字图像水印的识别具有实用价值。

Based on log-polar mapping, a new filtering method is designed and applied. In order to check the digital watermark embedded in digital images, the phase-only filter and our new filtering method are compared. Suppose the image embedded digital watermark is rotated ten degree and is scaled down ten percent, we fred the phase-only filter can＇t be used to identify the digital watermark in the digital images, but our new filtering method can be used to identify the digital watermark in the digital images. Some experiments are done, such as the image embedded digital watermark is rotated 45 degree and is scaled down 30 percent and so on. Experimental results demonstrate that the new filtering method is very useful for digital image watermarking.