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Computer and Robot Vision I

This chapter introduces image segmentation and its applications in various fields, including medical imaging, object localization in satellite images, face recognition, fingerprint recognition, and traffic control systems. Common methods for image segmentation, such as clustering, histogram analysis, edge detection, and region growing, are discussed. The technique of measurement-space-guided spatial clustering for image segmentation is presented, along with its advantages and limitations. Examples and comparisons are provided to illustrate the effectiveness of different segmentation methods.

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Computer and Robot Vision I

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  1. Computer and Robot Vision I Chapter 10 Image Segmentation Presented by:陳昱熙 r05522629@ntu.edu.tw 指導教授: 傅楸善 博士 Digital Camera and Computer Vision Laboratory Department of Computer Science and Information Engineering National Taiwan University, Taipei, Taiwan, R.O.C.

  2. DC & CV Lab. NTU CSIE

  3. 影像分割的應用 • 醫學影像 • 在衛星圖像中定位物體 • 人臉辨識 • 指紋辨識 • 交通控制系統 DC & CV Lab. NTU CSIE

  4. 常見的方法 • 聚類法 (聚類分析) • 直方圖法 • 邊緣檢測 • 區域生長 DC & CV Lab. NTU CSIE

  5. OUTLINE 在其他的地方分群之後，轉回原圖 直接在原圖上面分群 DC & CV Lab. NTU CSIE

  6. OUTLINE Measurement Space 原圖 DC & CV Lab. NTU CSIE

  7. OUTLINE 原圖 DC & CV Lab. NTU CSIE

  8. OUTLINE 在其他的地方分群之後，轉回原圖 直接在原圖上面分群 DC & CV Lab. NTU CSIE

  9. 10.1 Introduction • image segmentation: • partition of image into set of non-overlapping regions • union of segmented regions is the entire image • segmentation purpose: • to decompose image into meaningful parts (gray level、texture...)to application DC & CV Lab. NTU CSIE

  10. 10.1 Introduction (cont’) • rules for general segmentation procedures • region uniform, homogeneous w.r.t. characteristic e.g. gray level, texture • region interiors simple and without many small holes • adjacent regions with significantly different values on characteristic • boundaries simple not ragged spatially accurate DC & CV Lab. NTU CSIE

  11. 10.1 Introduction (cont’) • EX. segmentation based on valleys in gray level histogram DC & CV Lab. NTU CSIE

  12. holes 四個部分 ragged DC & CV Lab. NTU CSIE

  13. DC & CV Lab. NTU CSIE

  14. Joke DC & CV Lab. NTU CSIE

  15. 10.2 Measurement-Space-Guided Spatial Clustering • Clustering: • process of partitioning set of pattern vectors into clusters • set of points in Euclidean measurement space separated into 3 clusters • In some sense close to one another DC & CV Lab. NTU CSIE

  16. 10.2 Measurement-Space-Guided Spatial Clustering DC & CV Lab. NTU CSIE

  17. 10.2 Measurement-Space-Guided Spatial Clustering • no full theory of clustering • no full theory of image segmentation • image segmentation techniques: ad hoc, different in emphasis and compromise DC & CV Lab. NTU CSIE

  18. 10.2 Measurement-Space-Guided Spatial Clustering • The technique of measurement-space-guided spatial clustering for image segmentation uses the measurement-space-clustering process to define a partition in measurement space. So the character of the partitions is related to the measurement space DC & CV Lab. NTU CSIE

  19. 10.2 Measurement-Space-Guided Spatial Clustering 使用條件?優點缺點? DC & CV Lab. NTU CSIE

  20. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • histogram mode seeking: • a measurement-space-clustering process • homogeneous objects as clusters in histogram • one pass, the least computation time DC & CV Lab. NTU CSIE

  21. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • enlarged image of a polished mineral ore section DC & CV Lab. NTU CSIE

  22. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • 3 nonoverlapping modes: • black holes • Pyrorhotite • pyrite DC & CV Lab. NTU CSIE

  23. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) 深灰 (磁黃鐵礦) 淺灰(黃鐵礦) 黑 DC & CV Lab. NTU CSIE

  24. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • 2 valleys in histogram is a virtually perfect (meaningful) segmentation DC & CV Lab. NTU CSIE

  25. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • 原圖 • 切割後的結果 DC & CV Lab. NTU CSIE

  26. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • example image not ideal for measurement-space-clustering image segmentation 灰色們太相近了 DC & CV Lab. NTU CSIE

  27. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • histogram with three modes and two valleys Valley (boundary pixel) 很高(數量多) boundary 會不明顯 DC & CV Lab. NTU CSIE

  28. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • Undesirable: many border regions show up as dark segments 邊界取到很多 多餘的東西 DC & CV Lab. NTU CSIE

  29. 10.2 比較 DC & CV Lab. NTU CSIE

  30. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • 結論： • segmentation into homogeneous regions: not necessarily good solution • 在measurementspace上做clustering就算可以把某樣性質分成很明確的群聚，但轉換回原圖時卻常常會有holes跟boundaryragged的狀況 DC & CV Lab. NTU CSIE

  31. joke DC & CV Lab. NTU CSIE

  32. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • 那如果真的遇到那種histogram分群很不明顯的圖要怎麼辦? ? DC & CV Lab. NTU CSIE

  33. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • image of a section of the F-15 bulkhead DC & CV Lab. NTU CSIE

  34. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • Histogram of the image DC & CV Lab. NTU CSIE

  35. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • Five clusters: bad spatial continuation, boundaries noisy and busy DC & CV Lab. NTU CSIE

  36. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • three clusters: less boundary noise, but much less detail DC & CV Lab. NTU CSIE

  37. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • Recursive Histogram-Directed Spatial Clustering DC & CV Lab. NTU CSIE

  38. DC & CV Lab. NTU CSIE

  39. DC & CV Lab. NTU CSIE

  40. DC & CV Lab. NTU CSIE

  41. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) DC & CV Lab. NTU CSIE

  42. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • applied to the bulkhead image 取得算是漂亮， 雖然有點分太細， 導致region一堆 DC & CV Lab. NTU CSIE

  43. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • performing morphological opening with 3 x 3 square structuring element tiny regions removed, but several long, thin regions lost DC & CV Lab. NTU CSIE

  44. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • a color image DC & CV Lab. NTU CSIE

  45. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • recursive histogram-directed spatial clustering using R,G,B bands and other DC & CV Lab. NTU CSIE

  46. 10.2 Measurement-Space-Guided Spatial Clustering (cont’) • 那如果真的遇到那種histogram分群很不明顯的圖要怎麼辦? • 自己決定怎麼分群 • 把每個分群找出來，然後用opening DC & CV Lab. NTU CSIE

  47. joke DC & CV Lab. NTU CSIE

  48. 10.2.1 Thresholding • Kohler denotes the set E(T) of edges detected by a threshold T to be the set of all pairs of neighboring pixels one of whose gray level intensities is less than or equal to T and one of whose gray level intensities is greater than T DC & CV Lab. NTU CSIE

  49. 10.2.1 Thresholding (cont’) • 1. pixels and are neighbors • 2.min max DC & CV Lab. NTU CSIE

  50. 10.2.1 Thresholding (cont’) • The total contrast C(T) of edges detected by threshold T is given by DC & CV Lab. NTU CSIE

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