Visual cryptography scheme (VCS) is an encryption technique that utilizes human visual system in the recovering of the secret image and it does not require any complex calculation. Contrast has been a major issue of VCS schemes. Most copy machines have reversing function

in which can change a black image into a white one and vice versa. By means of the reversing operation

perfect black binary VCS with reversing can obtain ideal contrast. In this paper we conclude that we do not use existing VCS with reversing to construct an ideal contrast VCS for gray-scale images

then we show how to construct an ideal gray-scale VCS with reversing. In our scheme each participant is required to store a certain number of shares

and the number is same as that of binary VCS with reversing. Furthermore

the scheme guarantees that reconstructed image is correct since we perform certain runs operations.