植基於相鄰像素差值直方圖位移之可逆式資訊隱藏技術; A Reversible Data Hiding Scheme Based on Histogram Shifting Using Adjacent Pixel Difference

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/61020

Title:	植基於相鄰像素差值直方圖位移之可逆式資訊隱藏技術;A Reversible Data Hiding Scheme Based on Histogram Shifting Using Adjacent Pixel Difference
Authors:	金冠媛;Jin,Kuan-Yuan
Contributors:	資訊工程學系在職專班
Keywords:	可逆式資訊隱藏;直方圖位移;影像品質;Reversible data hiding;Histogram shifting;Visual quality
Date:	2013-07-22
Issue Date:	2013-08-22 12:09:55 (UTC+8)
Publisher:	國立中央大學
Abstract:	資訊隱藏(Data Hiding)為一種將機密訊息藏入媒體檔案中的方法，它可以將資料藏於檔案中而且傳送過程中不易被察覺有異的一種方法。接收端在收到偽裝檔案後，它可以透過其特定方法擷取傳送端藏入的機密訊息。若取出藏入訊息外也能將原始媒體檔案還原，即為可逆式的資訊隱藏(Reversible Data Hiding)方法。直方圖位移技術(Histogram Shifting Technique)是一種可逆式的影像資訊隱藏方法，這個方法利用像素統計直方圖中的峰點和零點位置，進行部分像素值的位移來隱藏機密訊息於影像中。回復時，採用反向方法，取出機密訊息外也能還原原始統計直方圖來還原原始影像。本篇論文主要介紹一個用於資訊匿蹤的可逆式資訊隱藏技術。這個技術利用影像中的每一組 2×2 像素區塊內具有接近像素值的特色，進行兩階段的像素差值運算，並搭配直方圖位移技術來隱藏機密資訊。在第一階段的運算中，它利用兩兩相鄰像素差值進行直方圖位移技術隱藏第一部分的機密資訊第二階段，它選取 2×2 像素區塊內兩兩相鄰像素中的大數差值進行直方圖位移技術隱藏第二部分的機密資訊。其中第一階段因為有較多的像素差值，可以隱藏較多資訊，而第二階段為了還原部分因第一階段改變的像素差值，採用反向運算的技術，這種技術除了隱藏資訊外也能降低偽裝影像的失真率。因為在嵌入機密資訊的過程中，我們的方法一直維持著 2×2 像素區塊內像素值大者恆大、小者恆小的結果，因此擷取機密資訊且還原原始影像的步驟即為嵌入機密資訊方法的反向操作。從實驗數據來看，我們跟過去文獻所提出的方法比較起來具有較佳的影像品質與資訊藏量。 Data hiding is a study of embedding secret data into cover media to produce a stego-media object, such that no one suspects the existence of the hidden data in the stego-media object. A data hiding method is reversible if the method can extract the secret data from the stego-media that is encoded by the method, and meanwhile, recover the cover media without any distortion. Histogram shifting technique is one of the reversible data hiding schemes that can be applied to image data hiding. It provides stego-images of good visual quality and high embedding capacity. In this technique, the pixel values between a pair of peak and zero points of the histogram are shifted or modified for data embedding, where the pair of peak and zero points are utilized to extract the embedding data and to recover the cover image completely. This paper presents a reversible data hiding scheme, which can embed secret bits into a cover image to produce a stego-image, and recover the cover image and the hidden secret bits from the stego-image. It is inspired by the fact that the pixel values in each block of 2×2 pixels are similar in a natural image. Both the embedding and the extraction procedures of the proposed scheme consist of two phases. The first phase uses the differences between neighboring pixel values and the histogram shifting technique to embed secret bits. The second phase identifies the largest pixel of each 2×2 block, and uses difference embedding and histogram shifting to embed secret bits. The input of the first phase tends to have more rooms (differences) to embed secret bits, and the output of the first phase creates an image of 2×2 blocks of larger neighboring differences. The second phase aims to use the opposite operations against the first phase to minimize some differences of the neighboring pixels in a 2×2 image block. The invariant of the proposed scheme is that, the maximum pixel and the minimum pixel in each block always remain the largest and the smallest respectively, during the embedding procedure. With the invariant, the extraction procedure can extract the secret bits and recover the original cover image from the stego-image by the reverse operations of the embedding procedure. The experimental results indicate that our scheme achieves better visual quality and higher embedding capacity than other schemes proposed by prior similar studies.
Appears in Collections:	[Executive Master of Computer Science and Information Engineering] Electronic Thesis & Dissertation

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