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    Please use this identifier to cite or link to this item: http://asiair.asia.edu.tw/ir/handle/310904400/111240


    Title: 應用於高動態範圍影像與多邊形模型之資訊隱藏技術
    Authors: 張嘉君
    Contributors: 行動商務與多媒體應用學系
    Keywords: 高動態範圍影像、多邊形模型、篡改偵測、可適應性資訊隱藏、認證、影像內插、 High Dynamic Range Images、polygonal models、tamper detection、adaptive information hiding、authentication、image interpolation
    Date: 2018
    Issue Date: 2018-07-30 13:39:24 (UTC+8)
    Publisher: 亞洲大學
    Abstract: 本文將資訊隱藏技術分別應用至高動態範圍影像與多邊形模型上,提出可適應性高動態範圍影像資訊隱藏演算法與區域式三維模型竄改偵測技術。
    在可適應性高動態範圍影像資訊隱藏演算法中,我們先沿用先前學者所提出的取樣方法取得參考像素,並先藉由最低有效位元取代技術將訊息嵌入至參考像素中,以有效提升訊息嵌入量。接著,利用參考像素將輸入影像切割成若干個重疊的區塊,並依據門檻值將每一區塊分成低複雜度與高複雜度兩類。低複雜度區塊內的每一像素,我們採用最低有效位元取代技術將訊息嵌入於其中,使得每一像素能保有基本的訊息嵌入量。高複雜度區塊則先使用影像內插技術取得內插影像,接著計算出內插影像與輸入影像的差值來估算訊息嵌入量,最後藉由另一門檻值的協助決定該像素的訊息嵌入方式,以避免失真程度過大。實驗結果顯示,相較於先前演算法,本文所提技術能擁有更高的訊息嵌入量,且偽裝影像有令人滿意的影像品質,使得可適應性資訊隱藏技術在高動態範圍影像上有進一步的發展。
    在區域式三維模型竄改偵測技術中,我們提出三套改良機制以增進三維模型訊息承載量、可嵌入訊息的頂點數量與竄改偵測的準確率,分別為訊息數字替換表的更新、嵌入比例的計算方式與產生更多可嵌入的頂點。在訊息數字替換表的更新機制中,我們修正秘密訊息的抓取方式,可使得訊息承載量增加11%。此外,我們也修正嵌入比例的計算方式,從原本相鄰頂點的周長變成最小邊長,此舉可將訊息承載量增加50%。最後,為了增加可嵌入頂點的數量與竄改偵測的準確度,我們僅採取部分相鄰頂點當成後續步驟之參考頂點使用,訊息承載量最高可增加至150%,可嵌入的頂點比例也從原本的24%至30%增加到36%至42%,竄改偵測的準確度也可有效提升。
    This thesis proposes two information hiding algorithms for high dynamic range images and polygon models separately. High capacity with imperceptible distortion is the basic goal for both algorithms.
    We first propose an adaptive information-hiding algorithm for high-dynamic-range images based on image interpolation and pixel-value differencing. The algorithm obtains the reference pixels from the input image and then embed the secret message into them based on LSB substitution method. Thereafter, a threshold is used to determine the block complexity and different embedding strategies are adopted for data embedding, either LSB substitution or pixel-value differencing. The embedding capacity for each pixel in complex block is obtained adaptively based on the difference between original and interpolated pixel value. Experimental results show that the proposed algorithm can have more embedding capacity accompanying with satisfactory image quality than previous algorithm.
    In our improved region-based tamper detection algorithm, three strategies are introduced to enhance the embedding capacity and the detection accuracy of our previous algorithm. First, the modified message-digit substitution table can increase the embedding capacity by 11%. Second, the modified embedding ratio generation method can be integrated to raise the embedding capacity by about 50%. Finally, the strategy adopting reduced number of reference vertices for authentication code generation accompanying with above two ones improves the embedding capacity up to 150%. Extensive experiments show that the proposed algorithm can achieve superior performance in terms of embedding capacity and tamper localization accuracy. Further, the model distortion between the original and the marked ones is small.
    Appears in Collections:[行動商務與多媒體應用學系] 博碩士論文

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