在藝術影像中作資料隱藏之研究

Abstract

藝術化影像(Art Images)是一種透過原始圖檔所產生出來的非相片般擬實(non-photorealistic)的影像。而馬賽克影像(Mosaic-Effect Images)則是藝術畫影像的一種，它由許多的幾何元件所構成，例如:磁磚、小圖和玻璃。在本論文中，我們研究了兩種馬賽克影像的產生與資訊隱藏技術。這兩種不同類型的馬賽克影像分別是磁磚畫與玻璃畫，前者是由許多大小、形狀相同的瓷磚組成，後者則是由不同形狀與大小的玻璃組成。在磁磚畫中，我們找到了三種可供資訊隱藏的屬性，分別是磁磚的旋轉角度、大小和材質。依據各個屬性的特性，我們將浮水印隱藏於磁磚的旋轉角度之中，以達到版權保護的目的。將秘密資訊隱藏於磁磚的大小之中以達到祕密傳輸的目的。最後將驗證資訊藏於磁磚的材質之中以達到影像與隱藏資訊完整性驗證的目的。由於此三種資訊隱藏的技術彼此獨立，所以使用者可以同時將這三種資料隱藏於磁磚畫中。在玻璃畫中，我們利用每片玻璃在生成時的樹狀資料結構(Tree Structure)來達到資訊隱藏的目的。我們利用的是樹的節點(Node)數目來作資訊隱藏，透過控制數的節點的數量，我們可以隱藏數個位元於其中。同樣的，我們也將此資訊隱藏的技術應用於玻璃畫的版權保護、秘密傳輸和影像完整性驗證。而對於各種不同的應用，我們會對資訊隱藏的流程作少許的修改。在本論文中，我們會對於磁磚畫和玻璃畫影像的生成和資訊隱藏提出完整的系統與流程，並透過實驗結果來證明此系統的實用性。

An art image is a non-photorealistic image created from a given image. A mosaic-effect image is a type of art image composed of geometric elements such as small images, tiles, and glass pieces. Two types of mosaic-effect images are investigated in this study, namely, tile mosaic images and stained glass images. Methods for automatic generation of these types of images and data hiding in them are proposed. In tile mosaic images, the tiles are squares of identical sizes, and are arranged regularly. Three different tile features, namely, orientation, size, and texture, are utilized for data hiding in the proposed methods. The orientations of tiles are used for copyright protection. The sizes of tiles are used for covert communication. And the textures of tiles are used for image authentication. A complete system to create tile mosaic images is also proposed, which may be employed to hide three kinds of data sequentially. In stained glass images, glass regions are generated by randomly sprinkled seeds and a region growing technique. Only one feature is used for data hiding in stained glass images, that is, the number of nodes of a tree constructed for pixel grouping in a glass region. A method for creating stained glass images and a system of three complete processes for watermarking, secret communication, and image authentication using the above-mentioned feature are also proposed. Experimental results show the feasibility of the proposed methods and systems.