資訊隱藏技術於數位內容保護之研究

Abstract

網際網絡的蓬勃發展，徹底顛覆了人類傳輸資訊的方式，越來越多的數位化內容已通過公開渠道傳播。由於合法和非法用戶可以方便地訪問數位內容，網路上傳輸的數位內容很容易遭受惡意的攻擊,因此數位內容的安全和保護問題應該得到更多的關注。爲了保障數位內容的安全傳輸，資訊隱藏技術已經成為近幾年研究的一個重要議題。在本文中，為保護不同的數位內容,我們分別針對機密資訊傳輸和數位圖像保護方面提出了相應的資訊隱藏方案. 每種我們提出的方法都會與一些其他現存方法比較，用以證明我們所提方法的優越性。 對於機密資訊傳輸的主題，我們首先提出了一種整合資訊隱藏和圖像壓縮的方法。在壓縮和資訊隱藏步驟，利用MBTC來嵌入機密資訊，並同時壓縮複雜的區塊。對於平滑的區塊，根據當前欲嵌入的機密資訊,圖像修復或BSOC技術將被用於機密資訊嵌入和壓縮。為了提高壓縮效果與資訊藏量，我們接著結合更豐富的圖像壓縮技術提出了一個可回復式的資訊隱藏方法。主要運用於將大量的機密資訊隱藏於經過向量量化 (VQ) 壓縮後的圖像。而搜索順序編碼 (SOC) 和狀態碼本映射器 (SCM) 技術則用於減小輸出碼流的大小。 對於數位圖像保護的主題，我們提出了一個雙重的數位浮水印機制用於保護彩色圖像。其中，不可見的強韌性浮水印和脆弱性浮水印將被同時藏入圖像分別用於版權保護和圖像認證。為了版權保護的目的，第一重強韌的浮水印將利用離散小波變換 (DWT) 嵌入於圖像的YCbCr色彩空間。另一方面，第二重脆弱的浮水印是利用改進後的LSB方法藏入於RGB色彩空間。強韌和脆弱的浮水印結合的機制，將更加適用於寶貴的數位圖像的保護。

Concerns pertaining to the security and confidentiality of the transmitted digital content have become critical over the past decade. Information hiding, which conducts the concealment of information within cover media is a common way that has been used frequently in modern. In order to preserve both secure secret data communication and digital media protection through the open channels, a study of information hiding techniques is presented in this dissertation. For the subject of information hiding for secret data communication, data hiding and image compression are seamlessly integrated into a single module to provide secure and efficient communications. We first propose a joint data hiding and compression (JDHC) scheme which is based on block truncation coding (MBTC), and search order coding (SOC) technique. To enhance the compression rate and hiding capacity, we further presents a reversible data hiding scheme for vector quantization (VQ)-compressed images. In this scheme, SOC and state-codebook mapping (SCM) technique are employed to reduce the size of the VQ index table and embed a large amount of secret data. For the subject of information hiding for digital image protection, we present a blind dual watermarking mechanism for color images authentication and copyright protection. In this scheme, discrete wavelet transform (DWT) in YCbCr color space and improved LSB replacement in RGB components are presented to embed invisible robust and fragile watermarks, respectively. The proposed information hiding schemes in this dissertation achieve the objectives of both secure secret data communication and digital media protection. The experimental results and comparisons with related schemes demonstrate that the proposed JDHC schemes achieve outstanding compression rate, visual quality, and hiding capacity for the different test images. On the other hand, the combination of robust and fragile watermarking makes the proposed dual watermarking mechanism suitable for protecting valuable original images in terms of both copyright protection and image authentication.