Improving visual quality for share images

© Springer Nature Singapore Pte Ltd. 2020. In this chapter, we focus on improving visual quality for extended VC, i.e., VC with meaningful shares. First, we discuss the case with binary secret images and cover images. Then we extend it to halftone cover images, in order to produce share images with better visual quality based on error diffusion. Finally, we extend the design to include a hidden watermark that can serve the authentication purpose.