基於易碎性浮水印技術之影像竄改偵測與自我還原

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Title:	基於易碎性浮水印技術之影像竄改偵測與自我還原 Image Tamper Detection and Self-recovery Using Fragile Watermarking
Authors:	廖子鈞
Contributors:	資訊傳播學系
Keywords:	影像驗證易碎性浮水印小波轉換竄改偵測 Image authentication fragile watermarking wavelet transform tamper detection
Date:	2017
Issue Date:	2017-10-17 11:07:02 (UTC+8)
Abstract:	本研究提出了一個能應用於影像竄改偵測與自我還原之易碎性浮水印技術。為了抵禦各種惡意攻擊，利用混沌映射所生成的對應序列，將由驗證資料與還原資料所組成的浮水印嵌入至影像中，並使用影像像素之間的關連特性來驗證影像。在竄改偵測的階段，則採用了分級檢驗的方式來提高竄改偵測的精確度並透過考慮鄰近區塊來進行兩階段自我還原，因應竄改巧合問題。此外，為了提高自我還原的影像品質，使用小波係數而非平均值作為還原資料來減少區塊效應並增加影像對比度。根據實驗結果顯示，本研究所提出的方法能有效的抵抗著名的惡意攻擊，如：拼貼攻擊、VQ 向量攻擊、平均值攻擊，並能維持高精準度的竄改偵測能力。且被竄改的影像亦能成功的自我還原，並具有高視覺對比度。 In this thesis, an effective block-based fragile watermarking method for image tamper detection and self-recovery is proposed. The proposed scheme embeds watermarks consisting of the authentication data and the recovery data into image blocks. To tamper detection and self-recovery, the embedding sequence is generated by using chaotic map and intensity-relation check to thwart various malicious attacks. In the tamper detection process, a hierarchical tamper detection strategy is adopted to achieve high tamper detection accuracy. A two-level self-recovery scheme is proposed by considering the 3×3 block-neighborhood to solve tampering coincidence problem. To reduce the smoothing blocking effect of recovered images, the wavelet transform coefficient is used to recover tampered image. It enhances the image contrast rather than using the average as recovery data. Experimental results show that the proposed scheme can effectively resist collage attack, vector quantization (VQ) attack and constant-average attack, while sustaining superior accuracy of tamper localization. Furthermore, the results show that the tampered images can be successfully self-recovered with high visual contrast.
Appears in Collections:	[Department of Information Communications & Graduate Institute of Information Communications ] thesis

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