  Pixel expansion and the quality of the reconstructed secret image has been a
major issue of visual secret sharing (VSS) schemes. A number of probabilistic
VSS schemes with minimum pixel expansion have been proposed for black and white
(binary) secret images. This paper presents a probabilistic (2, 3)-VSS scheme
for gray scale images. Its pixel expansion is larger in size but the quality of
the image is perfect when it's reconstructed. The construction of the shadow
images (transparent shares) is based on the binary OR operation.
