具有伪装图像像素不扩展的(2,2)视觉密码方案

针对视觉密码具有扩展度大, 分享为毫无意义的随机二值图像的问题, 提出了一种具有伪装图像的像素不扩展的（2,2）视觉密码方案。该方案对秘密图像分享时, 等概率随机抽取基本矩阵的一列, 然后将所得向量的每个元素分配给相应的分享图像。该方法用白色像素在恢复图像的黑色区域和白色区域出现频率的不同区分黑色和白色, 白像素在白色区域出现的频率比在黑色区域出现的频率高。解密后的秘密图像具有很好的视觉效果和安全性, 实验结果证实了该方案的有效性。

Image Size Invariant （2,2） Visual Cryptography Scheme with Disguised Patterns

To solve the problems of pixel expansion and meaningless of shadow images. a new （2,2） visual cryptography scheme is proposed, in which the shadow images with a certain significance are the same size as the original secret image. In this method, to share a pixel, one of the columns in the basis matrices is chosen at random. Eachelement in the chosen column is distributed to corresponding shadow images. This method is to use the frequency of white pixels in the black and white areas ofthe recovered image for interpreting black and white pixels by human visual system. The frequency of white pixels in the white area of recovered image will be higher than that in the black area. The recovered image has good visual effectiveness and security. Experimental results confirm the effectiveness of the scheme.