A Multilayer Steganographic Method Using Improved Exploiting Modification Directions Scheme

The exploiting modification direction scheme is a well-known irreversible steganographic method because of its high embedding efficiency and imperceptibility. The shortcomings of the exploiting modification direction scheme are the use of a ( $2n +1$ )-ary notational system secret digit and low payload. Some studies transform secret data into a sequence of secret digits in the 8-ary notational system to overcome the disadvantage of using a non-binary secret data problem, which also increases the payload. Additionally, some studies have proposed a two-layer embedding method to enhance data security, which also increases the payload. Besides, most of the EMD-based scheme has the fall of boundary problems when the pixel group is located in the boundary area, which increase the distortion of the stego-image. In this study, we proposed a multilayer steganographic method using an improved exploiting modification direction scheme, which includes the abovementioned advantages, using binary secret data, increasing the payload, enhance data security and preventing the fall of boundary problem. In addition, we demostrate a three-layer EMD-based data hiding example. The experimental results show that the proposed method achieves a high payload (approximately 4.5 bpp) and the quality of the stego-image satisfying the human vision system sensitivity (PSNR value is greater than 30 dB).