階層式線上多功能影像認證中心之研究

Abstract

由於數位科技的進步，數位影像可能會被非法複製或是私自使用。因此，發展數位影像版權保護的方法是很重要的課題。在本論文中，我們提出了階層式線上影像認證中心的概念，並在認證中心的系統裡提出和整合了新式的版權驗證方法及數位浮水印技術，以達到更有效率地保護影像版權的目的。首先，我們把線上搜尋影像及確認其版權歸屬的技術整合到認證機制中。第二，認證功能是由中央影像認證中心來執行發行認證的動作，不僅如此，我們還提出一個方法可用來檢查認證是否有遭受竄改。第三，我們發展了一個效率較高的方法，利用漸進式的浮水印比對來達到快速確認版權歸屬的目的。 此外，雖然現今常常使用數位浮水印的技術證明影像版權，但使用者需要同時保存原始影像及其所對應已加入浮水印的影像，這將會造成儲存空間的浪費，因此，發展可從已加入浮水印的影像回復原始影像的方法是需要的。基於這個目的，在最後我們提出了一個不失真可視浮水印的技術，良好的實驗結果證明了所提方法的可行性。

With the advance of digital techniques, digital images may be copied illegally or used without authorization. Therefore, it has become an urgent issue to develop methods to protect the copyright of digital images. In this study, the concept of hierarchical online image authentication centers is proposed. Not only novel authentication methods but also new digital watermarking techniques are proposed and integrated into the system for more secure and effective image copyright protection. First, techniques for online search of suspected images and verification of watermarked images are integrated into the system. Second, the functions of authentication and certificate issuing are implemented for use at the central image authentication center. Moreover, a method for certificate tampering detection is proposed. Third, a more efficient way for watermark verification by progressive image matching is developed. In addition, although digital watermarking techniques are commonly used for verifying the copyright of images, users need to keep both original images and corresponding watermarked ones. This results in waste of storage space. Therefore, a method for lossless recovery of original images from watermarked ones is desired. For this purpose, a lossless visible watermarking technique is proposed finally. Good experimental results showing the feasibility of the proposed methods are also included.