線條畫是影像抽象化的其中一種，由許多清晰、獨立的直線或曲線所組成，時常被用為是影像風格化的組成要件，甚至為影像理解提供了有用的線索之一。然而，從線條畫中判斷並選取有意義、重要的線條需要專業的技巧。現有的自動化產生線條畫系統對參數調整非常敏感，時常會取出過多或過少的線條，導致在產生線條畫時，使用者必須費一番功夫才能得到理想的結果。
我們提出EasyLineDraw，一個基於手繪的互動式系統，幫助使用者從雜亂的線條畫中選取有意義的線條。使用者僅需在原圖上畫出草稿，系統將會根據一致性與結構性從雜亂的線條畫中推論出使用者欲取出的線條。我們藉由測試各種不同的圖片來找出最合適的參數設定，實驗結果顯示我們的系統可以有效率地選取出符合使用者期望的簡單且重要的線條。

Line drawing is a style of image abstraction where the perception of image is conveyed using distinct straight or curved lines. Such concise representation not only constitutes the fundamental element in many artistic stylizations, it also provides valuable priors for advanced image understanding. However, extracting semantically salient lines is not trivial and mastered only by skilled artists. While a significant effort has been made in automatic generation of line drawing, existing methods are sensitive to different parameter settings, and frequently result in either excessive or insufficient lines. We present EasyLineDraw, a sketch-based interactive system to facilitate extracting effective line drawings from arbitrary images. The user simply has to provide a few scribbles, based on which the system automatically infers lines that are coherent and similar in structure from a detailed line image. We tested our system on a wide variety of images across different experimental settings. Results show that our system is efficient and extracts concise line drawings that conform to user’s expectation.

摘要 iv
Abstract v
List of Figures and Tables vii
Chapter 1 Introduction 1
Chapter 2 Related Works 4
Chapter 3 Algorithm 6
3.1 Stroke Classification 6
3.2 Matching 7
3.2.1 Matching for Coherence Strokes 9
3.2.2 Matching for Structure Strokes 13
Chapter 4 Results 16
4.1 Comparison 16
4.2 User Study 19
Chapter 5 Applications 22
Chapter 6 Limitation and Future Work 27
Chapter 7 Conclusion 29
References 30
Appendix A 32
Appendix B 35

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