A Study of Visual Cryptography by Using the Block Coding Techniques
| Autor: | min_huei Huang, 黃敏惠 |
|---|---|
| Rok vydání: | 2005 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 93 Visual cryptography is a method of sharing secrets by using naked eye. It’s an excellent solution under the situation of not being able to decrypt by computer. Traditionally, the size of share image that most visual cryptography methods result in will be much bigger than the original ones owing to the expanding of the gray image pixel, especially when it is applied in black-and-white and color image, the times of expanding is astonishing. This research proposes a technique of visual cryptography without the needs of pixel expanding. The methodology of this research is to use the concept of block encrypts which not only selects 2×2 sub-blocks to encrypt but also designs restricted rules. It can ensure the gray image pixel not to expand; besides, it also can make the quality of share image well proportioned and make it harder to find any configuration. Furthermore, it can enhance the degree of superimposition image and quality while encrypting. The technique not only encrypt designs restricted but also select 3×3 sub-blocks include noise in share image and produce two new share images. It let share images more security. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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