基於俄羅斯方塊的馬賽克畫：一種新的藝術畫與其在資訊隱藏上的應用

Abstract

在本論文中，我們以俄羅斯方塊(Tetris)為基本元件，創造了一種新的藝術畫，稱之為俄羅斯方塊馬賽克畫(tetromino-based mosaic images)，並研究自動產生這種影像與在其中做資訊隱藏的技術。在俄羅斯方塊馬賽克畫中，我們找到了兩種可供隱藏資訊的特性，分別是俄羅斯方塊的排列組合和其顏色的變化。首先，我們利用樹狀搜尋演算法來找出所有俄羅斯方塊的排列組合，藉由選擇不同的組合，將秘密資訊或浮水印隱藏於俄羅斯方塊馬賽克畫之中。同時，利用偵測邊界所得到的資訊，我們也提出了一種強化邊緣的方法來改善上述資訊隱藏技術所造成的雜訊。另一方面，藉由調整鄰近俄羅斯方塊的顏色，我們可以將秘密資訊隱藏於其中，達到秘密訊息傳輸與版權保護之目的。此外，我們也提出一種可視浮水印技術來保護俄羅斯方塊馬賽克畫的版權，而且所嵌入的可視浮水印可以無失真地移除之。基於這種浮水印技術，最後我們利用調色盤的對應關係，將秘密影像隱藏於浮水印區域，來達到影像秘密傳輸之目的。透過良好的實驗結果，我們證明了所提出方法的實用性。

A new type of art image is created in this study, namely, tetromino-based mosaic image. Methods for automatic creation of images of this type and data hiding in them are proposed. For the creation of tetromino-based mosaic images, we find all the possible combinations of tetrominoes by a tree enumeration algorithm. A tetromino database is constructed with different colors and tetromino combinations for image creation. We also propose a border enhancement process for improving visual effects of tetromino edges. For data hiding in tetromino-based mosaic images, we utilize two types of features of mosaic images, tetromino combination and color, to embed data. We can hide data by using distinct combinations of tetrominoes. An edge fitting method is used to enhance edge effects by adjusting combinations of tetrominoes using the information obtained by edge detection. In addition, the colors of tetrominoes are also used to hide data by shifting color values of tetrominoes slightly. For watermarking in tetromino-based mosaic images, we propose a removable lossless watermarking method by replacing the colors according to a mapping between two color palettes. Based on this invertible watermarking method, an image steganographic method is also proposed by replacing the colors of the watermark area according to the proposed mapping between the two color palettes. Experimental results show the feasibility of the proposed methods and systems.