Adaptive data hiding in edge areas of images with spatial LSB domain systems

This paper proposes a new adaptive least-significant-bit (LSB) steganographic method using pixel-value differencing (PVD) that provides a larger embedding capacity and imperceptible stegoimages. The method exploits the difference value of two consecutive pixels to estimate how many secret bits will be embedded into the two pixels. Pixels located in the edge areas are embedded by a kappa-bit LSB substitution method with a larger value of kappa than that of the pixels located in smooth areas. The range of difference values is adaptively divided into lower level, middle level, and higher level. For any pair of consecutive pixels, both pixels are embedded by the kappa-bit LSB substitution method. However, the value kappa is adaptive and is decided by the level which the difference value belongs to. In order to remain at the same level where the difference value of two consecutive pixels belongs, before and after embedding, a delicate readjusting phase is used. When compared to the past study of Wu et al's PVD and LSB replacement method, our experimental results show that our proposed approach provides both larger embedding capacity and higher image quality.