隨著網路及多媒體技術的日益精進，數位資訊於網路之傳輸較以往便利，多媒體數位資訊取得容易，因此數位資訊容易被加以拷貝及修改，以至於引發版權問題之爭議。為保護原創作者之專屬權益，需要經由一驗證機制，達到保護所有權及鑑別合法擁有者。透過數位浮水印技術可以在欲保護之資料中，藏入用來驗證版權的標記，一旦數位資料被非法擁有者持有，可透過演算法來驗證該持有人是否為合法擁有者。 本文提出了一個結合離散餘弦轉換及奇異值分解的多目標浮水印技術，為了達到浮水印強健性的目的，利用浮水印頻域的特性，將浮水印由空間域轉換至頻率域再嵌入浮水印。並且以AC(0,1)及AC(1,0)位置產生與嵌入驗證碼，透過新舊驗證碼之差異處，來判斷影像受竄改之位置。實驗結果顯示，我們提出的方法有很好的執行結果，也可以正確地偵測受竄改位置。 With the Internet and multimedia technologies progressing increasingly, it is more convenient to transport digital information in networks ever since. Multimedia digital information is acquired easily, so it is easy to copy and modify result in controversy of copyright protection. To protect the equity of original author via authentication mechanism, reach the legitimate owner of ownership and identification. By digital watermarking technology can be embed the sign of copyright on protection data. Once the digital data is held by the illegal owner, it can verify owner if he is legitimate. In this paper, we proposed a multipurpose watermarking based on Discrete Cosine Transform (DCT) and Singular Value Decomposition (SVD). We use the property of discrete cosine transform that spatial domain transform to frequency domain and embed watermark. And then the verification code is generated and embedded in AC(0,1) and AC(1,0), according to the difference of new verification code and old verification code can decide the place that is attacked on the cover image. The experimental results have good performs and also detecting malicious manipulations accurately on an image.
