The Study of High Security Watermarking Technology in Digital Images

Abstract

[[abstract]]隨著網際網路、多媒體與電子商務的快速成長，資訊交換變得既快速又方便，也由於資訊的取得太容易了，對於個人私密性資料的保護與智慧財產權的保障就顯的非常的重要。浮水印技術廣泛使用在檔案機密文件的保護，在過去的文獻研究中，大部分為文字和商標的隱藏，而且以需要原始影像的方式取出浮水印。本論文，提出兩層隱藏有效率的灰階影像浮水印演算法，浮水印的資訊隨機的嵌入在原圖中，我們幾乎不能從人眼偵測浮水印的資訊。第一層，用碼簿的觀念來隱藏浮水印。第二層，用空間或者頻率分佈加密法來隱藏重要資訊，提高安全性。兩層隱藏的技術，浮水印係數和私密鍵隱藏在原始影像裏，非正常取出程序，人們是很難偵測到浮水印資訊的，而且我們只要一些參數而不需要原圖就能取出浮水印。JPEG壓縮減少影像資料的大小，當壓縮後，浮水印的影像品質會降低很多，基於JPEG後的浮水印，我們使用頻率分配的觀點來加強浮水印影像品質。嵌入浮水印的影像和原始影像相互比較下，不易看出它們之間的不同處。由模擬結果知，浮水印的嵌入和取出PSNR都很高，影像品質相當好，對多媒體資料版權保護有很大的幫助。最後，將所有模擬結果展示在http://163.18.62.8/welcome.htm上，共計有六種浮水印嵌入與取出的方法，供大家參考比較。本技術將可培育具備整合多媒體、資訊安全與數位通訊專長的研發人才。[[abstract]]With the rapid growth of internet multimedia and electronic commerce system the interchanging of information is getting more and more convenient As it is so easy to get into others information the issues of the privacy information protection and copyright protection become more important in order to prevent unauthorized retrieval Watermarking techniques are widely used to protect the secret document in electronic form In the past literatures most of topics focus on "text" and "logo" data hidden based on comparison of original image and watermarked image to extract the watermark information In the thesis an efficient watermarking algorithm is presented with two layers hidden for gray level image watermarking The watermark information is randomly embedded into the original image We almost can not detect the watermarking information from human eye In the first layer the key information is found by using code book concept Further the key information is hidden to the watermarked image using the encryption consisting of spatial or frequency distribution in order to provide higher security With the double hidden technology the watermarking coefficients and privacy key are efficiently hidden into the composite image it is very hard to detect the watermarking information using un-normal extracting process And we only use some parameters rather than original image to extract watermark JPEG compression reduces a size of image data The quality of watermark information degrades very serious after JPEG processing We present a JPEG based image watermarking approach using the frequency dispensation concept to enhance the watermark quality The watermarked image becomes perceptually invisible as comparison with original image The simulation results show that PSNR of embedding and extracting image qualities are very high There is great helpfulness to protect the copyright of multimedia data Finally we show the six methods simulated results for the watermark of embedding and extracting in http://163 18 62 8/welcome htm This technology can train R&D personality for multimedia information security and digital communication techniqu