Unseen Visible Watermarking Based on Multi-Parameters Adjustable Gamma Correction

• Main Authors: Tzu-Chien Yang, 楊子見
• Other Authors: Dr. Chu-Hsing Lin
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/36402302541499038117

碩士 === 東海大學 === 資訊工程學系 === 99 === Along with the arrival of the digital age and progress of the information technology, digitalization is the major trend for nowadays society. With the prevailing of the Internet, it is more convenient and easier to download information than before. Therefore, patent infringement usually occurs and copyright protection has become one of the most important issues. Recently, the digital watermarking technology has been used in Metadata to prevent illegal downloading and to protect intellectual property rights of inventors. For authentication, one can extract embedded watermarks. Even though the illegal users steal the information, the extracted watermark can be retrieved by the owner to approve and determine the ownership of data. This thesis presents a digital watermarking that is different from the ordinary digital watermarking technology: it has both a visible watermarking and non-visible watermarking features. The embedded watermarking will change as the background color of the pictures to improve hidden effect. It is hard to discern the watermarked-image with the original cover image. Normally, the watermark is hard to detect in the watermarked-image, but if one changes the viewing angle, the hidden watermark is revealed. Besides, we use the Multi-Parameters Adjustable Gamma Correction (MPA-GC) to reduce the distortion of the watermarked-image in the retrieved watermark. The unseen visible watermarking image is easier to recognize by the human eye when the saturation of the image is increased. On the other hand, one can also apply the MPA-GC to reveal the hidden watermark after embedding it. The experimental results show that the hidden watermark image has very good image quality with the PSNR value over 50dB.