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    題名: 基於IntDCT之強健性數位影像浮水印技術
    其他題名: A study of robust digital image watermarking based on IntDCT
    作者: 謝旻諺;Hsieh, Min-yen
    貢獻者: 淡江大學電機工程學系碩士班
    謝景棠;Hsieh, Ching-tang
    關鍵詞: 浮水印;整數離散餘弦轉換;強健性;IntDCT;blind watermarking;robustness
    日期: 2006
    上傳時間: 2010-01-11 07:03:57 (UTC+8)
    摘要: 大部分浮水印的技術,要求取回嵌入的資訊時,不需要使用到原始的資料,這就是所謂的blind watermarking技術。本文提出一種簡單且有效的blind watermarking技術,在取出浮水印過程中不需原始影像與位置資訊。
    本文中採用H.264的轉換演算法,即整數離散餘弦轉換(IntDCT),以4x4的區塊大小進行轉換,可減低影像區塊效應的程度,藉以提高影像的品質。
    在本文提出的方法中,分別將強健性浮水印與錯誤偵測資訊,嵌入至DC與低頻AC中;強健性浮水印的部分,為了保持好的影像品質,在嵌入過程中,微量的修改DC值;錯誤偵測資訊嵌入的方法則是利用相鄰區塊之DC係數,估測並修改中心區塊之低頻AC係數。
    本論文將估測的方式應用到頻域中,能確保嵌入的浮水印在空間域中是不可見的。在取出的過程中,可以透過原先嵌入的錯誤偵測的資訊,指出影像被惡意竄改或資訊流失的部分;在取出浮水印時,即使影像遭受到破壞,利用錯誤偵測資訊,可在影像中拼湊出正確的浮水印。實驗結果顯示,本文所提出的浮水印系統具有高度的強健性,它能抵抗壓縮、切割、雜訊、模糊、亮度對比等各類訊號處理的攻擊。
    For most watermark applications, it is often desired to retrieve the embedded information without access to the host data, which is a so-called blind watermarking technique. Therefore, a simple and effective blind watermarking scheme is expected. In this paper, we present a kind of blind watermarking technique.
    The H.264 translate algorithm is used in this thesis. The Integer Decrease Cosine Transform (IntDCT), which uses 4x4 block to translate, is able to reduce the block effect.
    In the proposed method, we embedded the robust watermark and information of error detection into DC component and low frequency AC coefficients of DCT, respectively. For the robust watermark, we modify the DC coefficients slightly on embedding process. For the information of error detection embedding, we use the DC coefficients of neighbor blocks to estimate and modify AC coefficients of central block.
    We use the estimation in the frequency domain, and with that we can ensure that the embedded watermark is invisible in the frequency domain. In the extraction, we use the embedded information of error detection to find the missing or altered data of image. Even if the image is attacked, we still can use the information of error detection to find the correct watermark in extraction. Experimental results demonstrate the watermarks embedded with the proposed algorithm are robust to various attacks.
    顯示於類別:[電機工程學系暨研究所] 學位論文

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