基于DCT变换域的图像类水印认证算法

提出一种基于DCT变换域的图像类水印算法,该算法不对原始数据进行修改,只要通过环形自同构计算原始图像和认证图标DCT系数间的映射规则,在验证端再通过该映射规则来恢复认证图标进行认证.整个认证过程中不会对原始信息造成任何破坏,所以可应用于画面清晰度要求高的多媒体和认证系统中.实验结果表明,该算法与现有的空间域类水印算法比较,具有节省30%的存储空间;当待认证图像的PSNR>30 dB时,该算法提取出的认证图标的PSNR高4 dB;对JPEG等压缩图像进行认证时,不需要进行IDCT和DCT,提高了认证效率.

A Watermark-Like Authentication Scheme for the Images and Graphics Based on Discrete Cosine Transform Domain

This paper proposed a watermark-like authentication scheme for the images and graphics based on discrete cosine transform(DCT) domain.This scheme does not modify the original data but just determines a mapping rule to go from the DCT coefficients of the authenticating logo to the DCT coefficients of the original image by torus automorphism.In the whole authenticating process,no original information is destroyed.Therefore,this scheme can be used in multimedia and authentication system that require high quality images.The result of experiment shows that this scheme has the following advantages compared to the current watermark-like scheme based on spatial domain: This scheme can save 30% space in storing the mapping rule.When the PSNR of the original image is above 30 dB,the PSNR of the authenticating logo extracted by this scheme is 4 dB higher.The authenticating process of this scheme does not include IDCT and DCT operations for JPEG form at images.The authenticating speed is improved so much.