Abstract:

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. Each element 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 of the 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.

Key words: visual cryptography, basic matrix, shadow image, secret image