Application of Visual Cryptography in Watermarking

• Main Authors: CAI, WEI-JHE, 蔡瑋哲
• Other Authors: LIN, ZI-CHAO
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/51261360970268914692

碩士 === 吳鳳科技大學 === 光機電暨材料研究所 === 101 === Abstract The exchange of information becomes increasingly easy in cyber space with the booming of computers and smart phones. All people have to do is to upload images in digital data through network access to an online platform. However, there are concerns hidden behind this convenience. For example, one may hold the uploaded images for one’s own purpose without the permission of the original owner. Theft and tempering are the most common cases seen in cyber space. To solve the problems like these, a digital watermarking technique was developed. Therefore, when an image has a digital watermark embedded, the information embedded in the original image will be copied altogether. If there is a dispute, the watermark is extracted to protect the rightful owner of the copyright and portraiture right as a certification mechanism. However the action to embed information in the original image may damage its quality. As a result, the study was intended to preserve the quality of image after embedment and the recognition of the watermark after extraction. The watermark proposed here is different from the traditional ones because it is based on visual cryptography. A visually cryptographic watermark reduces the amount of information storage compared to traditional ones, and it requires less complicated calculations. Instead, it overlaps images for decryption, and experiments were performed to prove that it did improve the image quality and resistance. Keywords: Visual Cryptography, Watermark