Abstract: This paper presents a new algorithm for non-expanded share generation using RGVSS. In random grid visual cryptography scheme each pixel is treated as a grid. In probability based RGVSS the black appearing probability of each pixel with respect to cover image is used to generate non-expanded meaningful shares. The proposed method is modified form of probability based RGVSS. Here thresholding is applied to each of the blank shares to reveal its content. On overlapping blank shares the secret image is revealed. This will generate high contrast non-expanded shares which give almost perfect reconstruction of secret image.

Keywords: High contrast shares, Non-expanded shares, Random grids, Visual cryptography.