Embedding Security Keys in Images Using Digital Watermarks

• Main Author: 鄭有志
• Other Authors: Jan-Ray Liao
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/07038318343530733262

碩士 === 國立中興大學 === 電機工程學系 === 92 === The advances of computers and communication networks make digital content service such as digital document exchange, E-commerce, video on demand, and digital library very popular. Since digital data can be easily reproduced without any loss, copyright protection becomes an imperative requirement to prevent piracy. Digital watermarking has been proposed as one of the techniques to prevent data piracy and plagiarism. Digital watermarking is a novel and emerging technology. It has developed very quickly for the past few years. A digital watermark is a set of information that is robustly and imperceptibly embedded in the data to be protected. Applications include copyright protection and authentication. In the thesis, we developed two watermarking techniques using spread-spectrum technique. We interpreted the watermarking technology based on communication theory. The watermark was the signal to be transmitted. The frequency domain of the original image was the transmission channel. The attacks were regarded as channel noise. JPEG compression is the most widely used image compression technique because of its high compression ratio and reasonable image quality. In the multicast environment, we wanted to embed two different information to increase the security of images. Here, we developed an embedding method to embed two watermarks in the different bands. We used two different quantization tables to embed two keys in the same image, and realize embedding security keys in images using digital watermarks.