Tangent-Based Binary Image Abstraction

We present a tangent flow-based image abstraction framework that turns a color or grayscale image into a two-tone image, which contains only black and white color, but retains sufficient information such that the viewer can still recognize the main content of the original image by observing the output of a two-tone image. Usually, the relevant visual information is presented by the edge. Thus, the algorithm will enhance the edge content first by the tangent flow to preserve its detail. We use filters to smooth the input image to reduce the contrast in low contrast regions and enhance some important features. Then we turn the image into a two-tone image as output. We can reduce the size of the image significantly but retain sufficient information to capture the main point of the image through our method. At the end of our process, we provide a smoothing step to smooth the two-tone image. Through this step, we can get an artistic black-and-white image

Tangent Based Binary Image Abstraction

本篇研究論文提出一套基於影像正切值的演算法，將使用者輸入的彩色或灰階影像，轉變成為只有黑白兩色的二值化黑白影像，並且能保留影像當中的主體，讓觀察者就算只透過輸出的黑白影像，也能了解影像當中的主要內容為何。透過將影像平滑化去除瑣碎細節、強調明顯特徵，例如影像當中物體的邊界，最後將影像二值化，透過此方法能將影像的儲存空間大幅度的縮小，並且能保留足夠多的資訊讓觀察者得知影像主要內容。而本篇研究論文透過將黑白影像平滑化的步驟，使產生出來的黑白影像也具有藝術的風格。We present a tangent flow-based image abstraction framework that turns input colored image or grayscale image into a two-tone image, which contains only black and white color, but remains the sufficient information such that the viewer can still recognize the main content of the original image by observing the output two-tone image only. We use filters to smooth the input image in order to reduce the contrast in low contrast regions, and enhance some important features, for example, the edges. Then we turn the image into a two-tone image as output. We can reduce the size of the image significantly but still remains sufficient information to capture the main point of the image through our method. At the end of our process, we provide a smoothing step to smooth the two-tone image. Through this step, we can get an artistic black-and-white image.口試委員會審定書 # 誌謝 i 中文摘要 ii ABSTRACT iii CONTENTS iv LIST OF FIGURES vi Chapter 1 Introduction 1 Chapter 2 Related Work 3 2.1 Image Abstraction 3 2.2 Binary Image 4 2.2.1 Thresholding 5 2.2.2 Line Drawing 6 2.2.3 Halftoning 8 2.3 Some Other Works 9 2.3.1 Stylized Black and White Images from Photographs 9 2.3.2 Artistic Thresholding 9 2.3.3 Manga 9 2.3.4 Emerging Images 10 Chapter 3 Method 11 3.1 Pre-smoothing 11 3.2 Image Tangent Flow 12 3.3 Line Integral Convolution 14 3.4 Difference-of-Gaussians Enhancement 17 3.4.1 Gaussian Filter 17 3.4.2 DoG Filter 17 3.4.3 Enhancement 18 3.5 Binarization 18 3.6 Optional Smoothing Process 19 Chapter 4 Results 20 Chapter 5 Conclusions 24 Bibliography 2