To enlarge the capacity of the hidden secret information and to provide an imperceptible stego-image for human vision, a novel steganographic approach using tri-way pixel-value differencing (TPVD) is proposed in this paper. To upgrade the hiding capacity of original PVD method referring to only one direction, three different directional edges are considered and effectively adopted to design the scheme of tri-way pixel-value differencing. In addition, to reduce the quality distortion of stego-image brought from setting larger embedding capacity, an optimal approach of selecting the reference point and adaptive rules are presented. Theoretical estimation and experimental results demonstrate that the proposed scheme can provide superior embedding capacity and give secrecy protection from dual statistical stego-analysis. Besides, the embedded confidential information can be extracted from stego-images without the assistance of original images.