一种无像素膨胀的(3,3)视觉密码方案

A(3,3) visual cryptographic scheme without pixel expansion

针对视觉密码的像素膨胀问题,提出了一种无像素膨胀的(3,3)视觉密码方案,所给方案产生的分享图像与原始秘密图像具有相同的大小,不存在像素膨胀问题.所提出的视觉密码方案在对秘密图像分享的过程中每次处理4个像素,根据4个像素的颜色组成选择不同的分享策略,在每幅分享图像中相应地产生4个子像素.实验结果证实了所给方案能够很好地恢复秘密图像,同已有的视觉密码方案相比,所恢复的秘密图像具有很好的对比度.

To solve the problem of pixel expansion,a (3,3)visual cryptographic scheme without pixel expansion is proposed,in which the generated shares have the same size as the original secret image.The pro- posed schemes consider 4pixels at a time and generate 4output pixels in each share.So the decrypted image remains the same size as the secret image.According to the color composition of 4 input pixels,this scheme selects different sharing strategies to generate shares.The experimental results show that the pro-posed scheme can well recover the secret image.Compared with the existing visual cryptography schemes, the restored image has a good contrast.