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http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/32951
標題: | 區塊截斷碼與全像術於影像編碼及浮水印之研究 Image Coding and Watermarking Using Block Truncation Coding and Holography |
作者: | Chih-Jung Yu 余芝融 |
指導教授: | 貝蘇章(Soo-Chang Pei) |
關鍵字: | 半色調,區塊截斷編碼,數位浮水印,數位全像術, Halftoning,Block Truncation Coding,Digital Watermarking,Digital Holography, |
出版年 : | 2011 |
學位: | 碩士 |
摘要: | 隨著電腦與網路的快速發展,人們可以很輕鬆的經由電腦與網路存取數位影像。然而,對於一般未經壓縮處理過的數位影像,其往往需要佔用大量的記憶體空間,如此龐大的資料量也使得傳輸的效率降低。區塊截斷編碼(Block truncation coding)是一個很簡單且有效的影像壓縮方法,但比起現今常見的影像壓縮標準,區塊截斷編碼在壓縮率較大時,會產生明顯的區塊效應與紋理雜訊。因此,利用半色調能在視覺上產生近似連續色調的影像特性,結合半色調和區塊截斷編碼的影像壓縮方式,可以有效的提升影像的品質。在本論文中,我們改良了兩個結合半色調和區塊截斷碼的壓縮方法來提升輸出影像的品質。
有鑑於數位資訊具有被複製與存取的風險存在,為避免盜版及未經授權的資料被任意存取,故採取全像術的方式將浮水印資訊嵌入多媒體檔案內,以確保著作人的智慧財產權。基於傳統光學的全像術,需要較繁雜的儀器校準步驟,且需使用額外的全像片來記錄訊息,在分析成像資訊時亦較為麻煩,因此本篇論文中,介紹利用電腦計算全像術的原理來嵌入浮水印,如此要分析或存取影像訊號時,將較為快速且準確。 With the advancement of computers and the Internet, multimedia contents are very popular and easy to obtain. However, it often requires a large amount of memory storage to record the complex information contains in these multimedia contents. Thus, transmitting uncompressed digital media through the internet may be impractical. Block truncation coding (BTC) is a simple and efficient compression technology. However, the annoying blocking effect and false contour accompanied in high coding gain limit the application when compares to some modern compression technique. In order to improve the image quality, some halftoning techniques is combined with the BTC. In this study, we modify the schemes of two existing compression techniques which were based on BTC, and try to enhance the image quality. In addition, the surge of digital media is also creating a pressing need for copyright protection and content authentication. To avoid counterfeiting or unauthorized docu-ments being used, we could hide a set of auxiliary data, called digital watermark, into the original content. One of the watermarking techniques can be achieved by holography. While traditional holography is mostly obtained by optical interferometric equipments that require excessive setups, calibrations, and additional recording materials, the computer-generated holography is readily accomplished by computer manipulation. Hence, in this thesis, we also discussed several watermark embedding technique based on computer-generated holographic approach. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/32951 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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ntu-100-1.pdf 目前未授權公開取用 | 20.17 MB | Adobe PDF |
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