中間對折策略之雙影像可逆式資訊隱藏方法

Dual-image Based Reversible Information Hiding Scheme with Center Folding Strategy

吳致暉(Jhih-Huei Wu)

指導教授 ： 呂慈純

朝陽科技大學/資訊學院/資訊管理系/碩士(2015年)

摘要

雙影像技術近年來已被大量用於可逆式資訊隱藏方法中，大多數的資訊隱藏方法將重點放在如何尋找最佳預測值，使偽裝影像失真程度降低。多數方法在找到預測值後，會將k個位元的機密訊息，轉成十進制(或其他進制)的數值，此處的數值即為機密符號，並與預測值(或像素)進行相加(或相減)，完成嵌入動作。然而，本研究發現，機密訊息也是影響影像品質很重要的因素，機密符號過大可能導致偽裝像素與原始像素差異較大，因此，本論文利用中間對折策略縮小機密符號的數值，將縮小後的機密符號透過平均法嵌入兩張偽裝影像當中，以維持影像品質。另外，針對發生溢位問題的像素則以原始像素值取代，以減少不必要的影像失真。從實驗結果來看，本論文所提的方法與其他雙影像技術相比有相當不錯的表現，在相同藏量下，所提方法影像品質平均優於其他方法2 dB以上。再者，所提方法利用嵌入位元數k決定資訊藏入量，k值越大藏入訊息量越多。由實驗結果可以看出，在相同影像品質下，所提方法的藏入量較其他學者平均多約0.5 bpp以上。此外，所提方法不僅適用於實驗用影像，使用於一般影像上，其藏入量、影像品質及執行時間的表現也都很不錯。

關鍵字

中間對折策略 ； 雙影像技術 ； 可逆式資訊隱藏 ； 機密符號

並列摘要

In recent years, dual-image techniques have been widely used in reversible data hiding. Most data hiding methods focus on finding the best predictive value to reduce the degree of stego-image distortion. After finding the predictive value, most methods convert k secret bits to a decimal secret symbol, and add (or substract) the secret symbol to the predictive value (or pixel) for completing embedding procedure. However, this study found that the secret data also form a very important factor affecting image quality. If the value of the secret symbols is too large, they may cause larger differences between the stego-pixels and original pixels. Hence, this study employs the center folding strategy to reduce the value of the secret symbols. The reduced symbols are then embedded in two stego-images through an averaging method to maintain image quality. In addition, underflow/overflow pixels are replaced with the original pixels to reduce unnecessary image distortions. The experimental results show that the proposed method has fairly good performance compared to the other dual-image techniques. For the same embedding capacity, its image quality is also better than that of other methods by at least 2 dB on average. Furthermore, the proposed method determines embedding capacity with the k value. The larger the k value, the higher is the embedding capacity. The experimental results show that for the same image quality, the embedding capacity of the proposed method is better than that of other methods by at least 0.5 bits per pixel on average. The proposed method is applicable not only to experimental images, but also works well for general images in terms of embedding capacity, image quality, and execution time.

並列關鍵字

center folding strategy ； dual-image techniques ； Reversible data hiding ； secret symbols

參考文獻

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