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Sample Question 1 You are given 6 sample images, each containing either Object A or Object B. The feature vector representation of the objects in the image is given below: Image No. 1 2 3 4 5 6 Feature vector [24, 99] [21, 80] [23, 101] [120, 35] [111, 34] [123, 43] Object in the Image Object A Object A Object A Object B Object B Object B You have decided to use the Euclidean Distance to find the difference between two feature vectors. EuclideanDist n a i 1 (a) bi 2 i In comparing two feature vectors, the Euclidean Distance calculation will eventually give you a number. How do you interpret this number (i.e. what does it mean if the number is small / large)? [2 points] Answer: The smaller the number, the similar the two objects are. (b) You are given an image with the following feature vector: I = [40, 66] Try to classify the image (i.e. say that whether it contains Object A or Object B) using nearest neighbor method. Show your calculation and give reason for your classification. [6 points] Answer: Compare with Image 1: 36.7 Compare with Image 2: 23.6 Compare with Image 3: 38.9 Compare with Image 4: 85.8 Compare with Image 5: 77.9 Compare with Image 6: 86.1 Conclusion: Image I is most similar to image 2. Since image 2 contains Object A, then image I must contain object A as well. (c) Using the same feature vector as in part (b), try to re-classify the image, but now using the nearest centroid method. Do you get the same result? [7 points] Answer: Centroid for A: [23, 93] Centroid for B: [118, 37] Compare with Centroid A: 31.9 Compare with Centroid B: 83.2 Yes, the result is the same. Page 2 of 2 Semester 2 2006/2007 Image Processing