(2，2)-可视密存的最小象素方案

在Naor和Shamir提出的可视密存的基础上，给出了一种较简单的方案来解决(2，2)-可视分存中的象素膨胀问题.利用可视分存矩阵实现(2，2)-可视密存并证明了此方案的有效性，进而得到了实现此方案的象素膨胀的最小上界.同时给出了一个黑白象素分存时的一个选择原则，用它可增强分存图的对照度.其结果是新的.针对不同的象素膨胀值，编码密图“DES”.在附录中给出(2，2)-可视分存的结果，它们看起来象随机图.事实上，单一分存图，不能得到任何有关密图的信息，无论用什么方法和采用何种工具.其密图的恢复只要重叠两张分存图的透明片，它不需要加密知识也不需要密码计算.

A MINIMUM PIXELS SCHEME OF 2 OUT OF 2-VISUAL CRYPTOGRAPHY

Based on the work of Naor and Shamir, the author gives a simple scheme which 2 out of 2-visual cryptography to solve the pixel expansion problem in image sharing. The author can use visual sharing matrixes to carry on (2,2)-visual cryptography. The author proves the validity of the scheme. The minimum upper bound is also given in the paper. The result is new. The author want to encode the secret inage“DES”. The two shares generated by a visual cryptography scheme for new scheme for 2 out of 2 are given in the appendix with different value m. They look like random patterns and, indeed, no individual share provides any information, even to an infinitely powerful computer, on the original image. The original image is revealed by stacking together the two transparencies. However, it does not re quire any cryptography computation.