An Interactive Background Blurring Mechanism and Its Applications

淺景深是一種利用淡化背景雜訊來凸顯出主題的攝影手法，通常用在人像以及靜物攝影。將背景資訊淡化不僅可以產生特殊的視覺效果，也能保護背景人物的隱私權。我們提出一種新的聚焦演算法，模擬出大光圈相機所拍攝出的背景模糊特效。同時，也提供使用者一個簡單的介面，讓使用者給予簡單的互動，來切割出前後景、調整圖片的景深以及相機的設定。本系統使用的技術涵蓋了「懶人去背景工具」、「透明度分割」，以及產生深度資訊和失焦模糊特效，我們可從實驗結果看出此系統的效用。此外，我們也提供了一些在保護隱私權以及瀏覽照片方面的相關應用。Photographers usually take a shallow focus image to highlight the main subject in the picture and blur the distractions in the background region. Softening these distractions can not only produce special vision effect but also keep the privacy for people in the background. In this work, we develop a new defocusing algorithm to simulate the blur effect in the background caused by a wide aperture camera. We also design an easy-to-use interactive interface for users to segment foreground/background objects, adjust the depth of field for images, and assign camera settings. Techniques including lazy snapping, alpha matting, depth information generation and defocusing are integrated in the system. Experimental results show the effectiveness of the proposed mechanism. Furthermore, some applications on privacy preserving and photo browsing are also provided.CHAPTER 1 INTRODUCTION 1.1 MOTIVATION 1.2 REVIEW OF SOME PHOTOGRAPHIC TECHNIQUES 2.2.1 Circle of Confusion 2.2.2 Depth of Field 3.2.3 Shallow Focus 5HAPTER 2 RELATED WORK AND SYSTEM OVERVIEW 7.1 ADDITIONAL HINT TO CONSTRUCT THE DEPTH INFORMATION 7.2 INGREDIENT IN THE IMAGE TO CONSTRUCT THE DEPTH INFORMATION 9.3 SYSTEM OVERVIEW 10HAPTER 3 SUBJECT SEGMENTATION 11HAPTER 4 DEPTH MAP CONSTRUCTION 13.1 PERSPECTIVE 3-D BOX 14.2 POP-UP CARD 15HAPTER 5 IMAGE DEFOCUSING 17.1 DIAMETER OF BLUR SPOTS 17.2 DEFOCUS BLUR 19.3 SHALLOW FOCUS IMAGE SIMULATION 21HAPTER 6 EXPERIMENT RESULTS AND APPLICATIONS 25.1 EXPERIMENT RESULTS 25.1.1 Defocus blur method proposed in the system comparing with other blur filter results 25.1.2 Depth variation in the background 28.1.3 Case with object in front of focus 30.2 APPLICATIONS 33.2.1 Privacy Preserving 33.2.2 Partial Viewing 34.2.3 Image Transition at Photo Browser 36HAPTER 7 39ONCLUSION AND FUTURE WORK 39EFERENCE 4