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    Please use this identifier to cite or link to this item: http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/102607


    Title: 基於小波轉換且對比強化之可逆可視浮水印技術研究
    Other Titles: Wavelet-based reversible and visible image watermarking scheme
    Authors: 蔡瀚威;Tsai, Han-Wei
    Contributors: 淡江大學資訊工程學系資訊網路與通訊碩士班
    陳建彰;Chen, Chien-Chang
    Keywords: 浮水印;小波轉換;對比強化;visible watermark;reversible watermark;Wavelet transform
    Date: 2014
    Issue Date: 2015-05-04 09:59:56 (UTC+8)
    Abstract: 本論文提出一個以小波轉換為基礎,輔以改良對比度之可逆浮水印技術。此嵌入技術可將浮水印影像嵌入至數位影像中,而僅需使用嵌入浮水印後的掩護影像及嵌入過程所產生的例外紀錄,即可還原獲得原數位影像,並獲得已嵌入的浮水印影像。
    本論文之嵌入浮水印演算法步驟如下。首先將欲嵌入浮水印之影像以鄰近的四個像素為一組分割成四張相似的影像。接下來對分割後的影像分別使用小波轉換處理。然後將用小波轉換處理過後的影像取LL的區塊使用本論文所提之改良式對比強化浮水印嵌入技術嵌入浮水印。之後使用反小波轉換將嵌入浮水印後的小波影像轉換回影像。最後只要將轉換回來的影像合併,即可得到嵌入浮水印的影像。
    安全性方面,本論文將原影像分割成四張相似的影像,取其中一張作為浮水印嵌入的參考,選取另外三張嵌入浮水印,提高了沒有本論文的方法時欲還原成原本影像的困難度,與其他論文比相對來說更加安全。
    A visible reversible image watermarking scheme embeds visible watermark into digital images for ownership identification and the embedded watermark can be removed to recover the original image. The proposed scheme first partitions the cover image to four similar images with half size in width and height. These 4 images are classified to two sets, fixed set (FS) and watermarked set (WS), and each image is then applied to forward wavelet transform for acquiring 4 low-pass subimages for embedding watermark image. The number of FS and WS deter-mines the stability or visibility of embedded watermarks. The coefficients in FS are stationary and the watermark image is embedded into low-pass coefficients of WS based on low-pass coefficients of FS. Experimental results show that the proposed scheme has good watermark similarity and good extraction result under cropped or noise attacks.
    Appears in Collections:[資訊工程學系暨研究所] 學位論文

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