數位影像編修竄改及其偵測

Abstract

你可曾自己修改不滿意的數位照片？如果有，那你就算接觸過數位影像的編修了。隨著科技進步，電腦能提供的運算能力越來越強大，伴隨方便、容易上手卻又擁有強大功能的數位影像軟體，有經驗的使用者就能夠將數位多媒體資料轉變成為他們所想要的形式，而以影像方式呈現的媒體為其大宗。隨之而來且日益重要的是如何去偵測數位影像編修合成竄改的問題。 在大多數的時候，數位影像的修改是不容易被發現的，編修過的痕跡往往會被其作者盡力消去，避免其容易被分辨出來。然而，對影像的後製過程幾乎都會留下些蹤跡，雖然對人的肉眼而言難以察覺。基於這個想法，這篇論文中提出了幾個方式以及想法來應付並偵測數位影像的編修痕跡，但是並不藉由廣為人知的數位浮水印技巧。在各種偵測方式中，其有效性以及結果將會於相對應的章節中 做詳細的探討。

Have you ever edited some unsatisfied digital photographs of yours? If the answer is yes, then you have made some digital tampering. With powerful computer and mighty software, seasoned users could turn digital media into what they want. The detection of digital tampering has become a crucial problem. In most of the time, digital tampering is not perceptible by human; however, some traces of digital tampering may be left in the media during the process. Based on this idea, several detection methods are proposed in this thesis to against various common digital tampering without any help of embedded information such as the well-known atermarking technique. Effectiveness and results will be presented in each method, robustness will also be discussed.