Reversible Dual-image Data Embedding on Pixel Differences Using Histogram Modification Shifting and Cross Magic Matrix

Data hiding has been used to send sensitive information that is hidden in another signal/object, such as in audio or image data. The cover and marked signals are indistinguishable, so that they remain imperceptible to the human senses. Chang et al. proposed a dual-image data hiding method, which uses a magic matrix to embed secret data. Even though the peak signal-to-noise ratio (PSNR) of the image quality is 45 dB, the embedding capacity can only reach 1 bit per pixel. This study proposes a two-phase scheme for dual-image hiding with reversibility. Phase 1 embeds data on pixel differences, using a histogram-modification-shifting method and phase 2 uses a cross magic matrix to conceal secret digits on the plane with differences in its four quadrants. The proposed method can not only significantly improve the image quality measured by the PSNR but also can preserve the embedding capacity at a high level.