Watermarking techniques for halftone images

• Main Authors: Yen-Hung Chen, 陳彥宏
• Other Authors: Jeng-Shyang Pan
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/07411597739505146463

碩士 === 國立高雄應用科技大學 === 電子與資訊工程研究所碩士班 === 93 === In the era of internet, documents in either color level or gray level are easily delivered in vast amount than before. To protect the copyright and ownership of those documents, digital watermarking is often used to prevent the illegal duplication. In this study, author has been interested in achieving data hiding of halftone images. Also, two watermarking algorithms were proposed to declare the authorship ( a binary mark ) of halftone images. The first author’s research topic is rooted on self similarity in fractal theory. Because this watermarking algorithm using self similarity utilizes the stochastic property of halftone image, it is resistant to cropping and corruption due to human marking. The secondary author’s research topic is to develop a lossless watermarking technique for halftone images. This proposed algorithm not only has the ability to achieve copyright protection, but also can exact recover the original halftone image with legal authorization. Experimental results show that the concept of pattern substitution in conjunction with an appropriate block cutting on a halftone image makes possible the positive recovery of the original halftone image after the extraction of a watermark.