高隱藏量之無損型資料隱藏法及其JPEG上之應用

High capacity lossless data hiding and its application in JPEG

李宗諴(Tzung-Shian Li)

指導教授 ： 林易泉

國立虎尾科技大學/電機資訊學院/光電與材料科技研究所/碩士(2010年)

https://doi.org/10.6827/NFU.2010.00006

摘要

資料隱藏法是一種將秘密資訊藏入數位影像的方法。若隱藏後的影像在解碼端按照合法程序能夠回復到與原始影像一模一樣，則稱這樣的演算法為無損型，可用於智慧財產權保護，影像資料的驗證方面。本論文提出了兩個新的無損型資料隱藏法，有著高隱藏量與高影像品質的優點。本論文提出的第一個演算法是基於有名的直方圖平移法，我們利用四分樹及二元樹等的樹分割法將影像分成若干適當的區塊，有效改進直方圖平移法中隱藏量不足的缺點。在本論文中也證明了將影像分成若干區塊能提高隱藏量的原因。第二個提出的演算法則是基於平移次取樣後的差值直方圖。我們利用內插法及雙線性內插法有效提升次取樣後參考影像與目標影像間的相關係數，因而使參考影像與目標影像間差值變小，使差值直方圖變集中，從而得到高隱藏量的目的。實驗結果顯示，我們的兩種方法不僅提升了原方法的隱藏量，也提高了隱藏後的影像品質。此外本論文所提出的方法很簡單，其計算複雜度也是很小的。最後本論文將所提供的演算法實做在JPEG格式中，畢竟JPEG格式是現在影像資料最普及的格式，我們以此來證明所提出的演算法之實用性。

關鍵字

無損型資料隱藏 ； 四分樹 ； 線性內插 ； JPEG

並列摘要

In this thesis, we propose two novel lossless data hiding algorithms for images, which the original host image can be exactly recovered from the marked image after the hidden data has been extracted. First we propose a histogram shifting technique based on a tree segmentation on the spatial domain of images, which divides input image into many different sized blocks, and utilizes the zero or minimum points of the histograms of the blocks to expand hiding capacity. And the reason of increasing capacity is also proofed in this thesis. The second proposed algorithm considers shifting the histogram of the difference values between the sub-sampled target pixel intensities and their interpolated counterparts to hide secret data. The shifting of the histogram of difference values is carried out by modifying the target pixel values. As compared to other schemes, the proposed sub-sample method can make more utilization of the correlation between nearby pixels in an image via simple interpolation techniques to increase embedding capacity without sacrificing much distortion for data hiding. The experimental results demonstrate that the two proposed methods not only provide larger embedding capacity than other histogram shifting methods but also maintain high visual qualities. Moreover the computational complexity of the proposed method is low since only simple arithmetic computations are needed. Finally, we implement the proposed lossless data hiding method in JPEG standard to demonstrate the practicability of our algorithms.

並列關鍵字

lossless data hiding ； quad-tree ； bilinear ； JPEG

參考文獻

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