Variable Threshold Based Reversible Watermarking: Hiding Depth Maps

This paper presents a lossless data hiding approach based on integer wavelet transform and variable threshold for a novel application of watermarking. In this novel application, a depth map of an object obtained from sequence of 2D images is secretly embedded in one of the 2-D images for subsequent 3-D analysis after transmission. Additionally, for efficient generation of the depth map, we also propose a new focus measure based on discrete cosine transform (DCT) and principal component analysis. The proposed approach is able not only in extracting the depth map, but also recovers the cover image. Experimental results show the capability of the proposed approach of secretly transmitting and retrieving the depth information. The employment of this novel idea of hiding depth maps in corresponding 2-D cover images could be helpful in medical and military image processing, security based stickers, mobile advertizing, image vision, law enforcement, etc. Additionally, if the depth map is generated through a standard approach, it could also help in the authentication related applications of the cover image.