High-capacity reversible image steganography based on pixel value ordering

Abstract

In this study, an improved reversible image steganography method based on pixel value ordering (PVO) is proposed to improve the steganographic capacity. Before the steganography process, three continuous and neighboring pixels are regarded as one group for sequencing, where the maximum and minimum values are adopted for difference value calculation and the number of difference values is recorded. The pixels with more steganographic difference values in rows or columns are determined, after which the steganography and ciphertext retrieval steps are performed in the rows or columns of the digital image. The experiment results prove that the method replaces the block structure in frame selection by groups of continuously read pixels, i.e., every three pixels form a pixel group where two bits of confidential information can be hidden, thus improving the steganographic capacity effectively. Comparisons with other PVO hiding schemes confirm the superiority of the proposed scheme, which has a higher capacity and maintains an acceptable peak signal-to-noise ratio (PSNR).