隨著電腦科技的持續進步，數位影像在生活中的應用也逐漸增加，數位影像版權的保護也越來越受到重視。數位浮水印技術是目前針對數位影像或者數位影片的版權保護而廣為使用的技術。然而，當資料受到轉換或攻擊時，如何保護浮水印不受到破壞仍然是現今浮水印技術重要的議題。因此，本篇論文提供了一個基於影像特徵與離散小波轉換的數位影像浮水印技術，它能有效抵抗影像的旋轉與縮放等影像幾何失真的攻擊。首先，原始影像經由離散小波轉換後，將指定的浮水印嵌入至其中的中頻區域，同時我們利用Harris演算法將小波轉換後低頻的特徵點擷取出來，並且利用了整張影像的高頻強度，將不同影像的特徵點數量控制在一定的範圍內，最後將另一浮水印嵌入至特徵點當中。若目標影像遭受到旋轉或者縮放攻擊時，利用影像特徵點不變的特性，我們可以利用嵌入特徵點的浮水印計算出中頻區域浮水印的位置並將之取出。為了檢查浮水印系統的強韌性，我們測試了影像不同角度的旋轉以及不同倍率的縮放並且加上了一般常見的浮水印攻擊手段如加入高斯雜訊、JPEG壓縮及影像裁剪。實驗結果顯示在這些測試之下浮水印依然有著良好的強韌性，達到了強韌型浮水印系統的優良效果。

As the applications of digital images become much common in our lives, protection of digital images’ content or copyright is more emphasized. Digital watermarking is a well-known technology that usually embedded a specific watermark on the image. However, it is still a challenged issue for finding any proper algorithm which can against variant image processing operations or attacks to the watermarked image. In this thesis, a robust digital image watermarking technology based on image feature points and wavelet transformation was proposed. The proposed watermarking method provided effectively the capability of resisting geometric distortion of images such as rotation and scaling. Firstly, the image is decomposed into four subbands by Haar wavelet transform. A specified watermark is embedded on the middle frequency band. At the same time, the image is divided into blocks and done the wavelet transform for each block. The feature points of each block are extracted from the transformed low frequency band by Harris’ method. The transformed high frequency band is used to evaluate of the number of feature points must be kept for the corresponding block. The locations of these feature points and the number of features for each block is composed as the second watermark and to be embedded. To examine the robustness of the proposed method for geometric distortions and attacks, the combination of various rotation angles, scaling factors, and image processing operations such as JPEG, noising, copy-and-paste of the watermarked image have been tested. The experimental results show that the proposed method is very encouraged.

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