影像秘密分享技術是一種共同保護秘密影像的策略，將要保護的秘密影像經過運算處理後成為無法窺伺出原圖的分享影像。其中在以布林函數為基礎的方法中，(n, n)是最為常見的分享方式，此方法為將要分享的秘密影像加密並分享給n個參與者，若要還原回秘密影像則需要n位參與者皆參與的秘密影像分享方法，但以此為門檻的方法發展至今卻仍然無法做到漸進式影像秘密分享的實踐。
本論文提出以(n, n)為基礎之漸進式分享與還原，不需要蒐集滿所有的分享影像即可進行還原動作。以兩個門檻為例，在(n, n)門檻值下分享n張秘密影像，透過本文所提出的演算法產生2n張分享影像，還原時若蒐集n張分享影像即可依序還原出秘密影像的高位元資訊，若要還原完整影像則必須蒐集所有分享影像後才能將秘密影像依序還原。

Image secret sharing technology is a strategy for jointly protecting secret images. The secret images are protected by sharing shared images among participants, and gathering enough shared images can recover secret images. Therefore, the (n, n) secret image sharing method shares n secret images among n participants, and gathering n shared images can perfectly recover the n secret images. 
The (n, n) secret image sharing problem can solve by conventional Boolean calculation easily. However, none of them deals with progressive recovery. This study proposes a Boolean-based (n, n) progressive secret image sharing method, with the property of gathering some shared images recovering part of secret images information. The proposed two-threshold structure can share n secret images to 2n shared images, and gathering first n shared images can recover rough information of these secret images. Moreover, gathering all 2n shared images can perfectly recover all secret images. Furthermore, the proposed structure can extend to different thresholds. Experimental results show that the proposed structure can share n secret images to tn shared images with t different progressive recovering steps under limited processing time.

目錄	IV
圖目錄	VI
表目錄	VII
第一章 緒論	1
1.1 研究背景與動機	1
1.2 論文架構	4
第二章 相關研究	5
2.1 基於布林函數之多重影像秘密分享技術	5
2.2 Chen和Wu的方法[6]	7
2.3 Chen和Wu的方法[7]	9
2.4 Chen等學者的方法[19]	11
第三章 本論文提出方法	14
3.1 分享流程	14
3.2 還原流程	17
3.3 探討本文提出之方法	20
第四章 實驗結果及比較	24
4.1 實驗結果	24
4.2 比較與討論	28
第五章 結論	30
參考文獻	31
附錄	34
圖 2.1 Barbara和亂數影像進行XOR運算後結果	6
圖 2.2相同影像進行XOR運算後結果	6
圖 2.3 Barbara和全黑影像進行XOR運算後結果	7
圖 2.4 經過XOR運算結果	9
圖 3.1分享流程示意圖	16
圖 3.2還原流程示意圖	19
圖 3.3 高位元影像位元標記示意圖	21
圖 3.4 未重排之高位元分割影像示意圖	21
圖 3.5 低位元影像位元標記示意圖	21
圖 3.6 未重排之低位元分割影像示意圖	22
圖 4.1分享四張秘密影像結果	25
圖 4.2本方法的分享影像及分享影像進行XOR運算後結果	26
圖 4.3本方法的高位元影像及3位元的高位元影像	27
表 4.1多重秘密影像分享方法比較表	29

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