基于HVS的抗统计分析的小波域密写

针对通过分析小波系数直方图特性的变化能侦测到小波域图像密写信息的存在性这一问题和人眼对图像强纹理不敏感的特征,提出了一种基于HVS的抗统计分析的小波域密写方法。该方法先将载体图像分成固定大小的小块,对每一小块进行基于提升策略的整数小波变换。根据符号和奇偶值将非零小波系数分为2类,分别表示1和0。如果嵌入的秘密比特与小波系数表示的信息不同,修改小波系数使它变为另一类,否则不变。在强纹理块,2层以上的小波系数用来嵌入更多的秘密信息以保证良好的视觉隐蔽性。最后,通过小波逆变换获得载密图像。实验结果表明,该密写方法不但能有效地保持小波系数直方图的特性,而且具有良好的视觉质量。

A Steganography on Wavelet Domain Based on HVS Against Statistical Analysis

Concerning the problem that the existence of secret information of the stego-image on wavelet domain is subject to detection by histogram analysis for wavelet coefficient,and the visual property that human eyes are less sensitive to textured areas of an image,a novel steganography on wavelet domain against statistical analysis based on HVS(human visual system) was proposed.First,an image was divided into blocks of prescribed size,and every block was decomposed into wavelet using IWT(integer wavelet transform) based on lifting scheme.Then,all nonzero wavelet coefficients were classified into two categories according to their sign and parity,and marked by steganographic 0 and 1 respectively.If the identifier of wavelet coefficients was different from secret bit,it would be modified to the opposite one,otherwise unchanged.And more secret information was in turn embedded into 2 or more level wavelet coefficients in textured blocks so that good visual imperceptibility was obtained.Finally,the stego-image was obtained by the inverse wavelet transform.From the experimental results,the proposed method effectively keeps the identity of histogram for wavelet coefficients and maintains a good visual quality of stego-image.