Gradient domain binary image hiding using color difference metric

In this paper, we propose a method for hiding binary images into the gradient domain of a host color image, by modifying the gradient vectors to a chosen hiding vector orientation in CIELAB color space. The color changes are constrained by the just-noticeable difference (JND) to guarantee the imperceptibility of embedded data. Generally, one pair of pixels is used to embed one binary bit. Using multiple hiding vectors, indexed color images or multiple binary images can be embedded in one image simultaneously. Hence high capacity can be achieved in comparison with the existing methods.