Lossless Information Hiding in Images

2.4. Histogram Modification–Based Schemes

2.4.1. Original Histogram Shifting–Based Scheme

Ni et al. [22] proposed a novel reversible algorithm based on histogram shifting techniques. The algorithm first finds a zero point (no pixel) and a peak point (a maximum number of pixels) of the image histogram. If zero point does not exist for some image histogram, a minimum point with a minimum number of pixels is treated as a zero point by memorizing the pixel grayscale value and the coordinates of those pixels as overhead information. Ni et al. [22] shifted the peak point toward the zero point by one unit and embedded the data in the peak and neighboring points. Note that the original peak point after embedding disappears in the histogram. Hence, to ensure ...