4.This question is about computer vision.

4. a. Briefly define what is meant by image segmentation in computer vision. [3 marks) b. One method of image segmentation is clustering. Write pseudo-code for the k-means clustering algorithm. [6 marks c. The RGB channels for a 3-by-3 pixel colour image are shown below. 5 10 10 10 15 10 15 30 25 R= 10 20 10 G= 10 20 5 B = 15 15 10 5 30 30 5 10 10 15 5 10 Apply the k-means clustering algorithm to this image in order assign each pixel to a region based purely on its colour. Assume that (i) the method used to assess similarity is the sum of absolute differences (SAD), (ii) there are two clusters, and the cluster centres are initially assigned the following RGB values: (10, 10, 10) and (30, 20, 10). [6 marks) d. For each of the nine pixels of the image defined in question 4.c write down the feature vectors that would be used to perform image seg- mentation using k-means clustering based on both colour and location information. [4 marks e. Name three alternative, region-based, algorithms that could be used to segment the image using both colour and location information. [6 marks