Invertible secret image sharing for gray level and dithered cover images

Abstract

Secret image sharing approaches have been extended to obtain covers from stego images after the revealing procedure. Lin et al.’s work in 2009 uses modulus operator to decrease the share image distortion while providing recovery of original covers. Their work use gray level or binary image as cover. Stego images have approximately 43dB and 38dB PSNR for gray level and binary covers respectively. Lin et al.’s work in 2010 provides enhanced embedding capacity but does not support binary covers. Gray level covers’ PSNR is reported approximately 40dB. The proposed method enhances the visual quality of stego images regardless of intensity range of covers. Exploiting Modification Direction method is used to hide the shared values into covers. The method also utilizes modulus operator to recover original cover pixels. Stego image PSNR is approximately 47dB for gray level covers. The method provides 4–7dB increase respectively on the stego image quality compared to others. Stego images have also higher PSNR (43dB) for dithered covers. The proposed method generates stego images with higher PSNR regardless of the intensity range of the cover image.