Threshold Visual Cryptography Schemes With Tagged Shares
Pei-Ling Chiu, Kai-Hui Lee · IEEE Access · 2020
The appearance of shares encoded by traditional visual cryptography is not easy to distinguish and meaningless. It means the shares cannot be managed efficiently nor user-friendly. A tagged visual cryptography scheme (TVCS) provides additional tag images for the shares and decodes the tag images by folding up a single tagged share. A TVCS allows users to efficiently manage shares and greatly increases the user-friendliness of the shares. Previous researches have focused on codebook-based and random-grid-based TVCS approaches, but the visual qualities of recovered secret images and tag images can still be improved. Therefore, this study aims to provide better visual quality of recovered images by improving on previous methods. Moreover, the proposed approach supports adjustable visual qualities of recovered secret images and tag images. In this study, we theoretically analyze the performances of the proposed approach and then demonstrate implementation of the approach.