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Representation and Description Theoretical Assignments Question 1: Plot the signature of a square boundary using the tangent angle method discussed in Section 11.1.3 of the text book. Question 2: Find an expression for the signature of each of the following boundaries, and plot the signatures a) an equilateral triangle b) a rectangle c) an ellipse Question 3: Draw the medial axis of a) a circle b) a square c) a rectangle d) an equilateral triangle Question 4: Give the smallest number of statistical moment descriptors needed to differentiate between the signatures shown in slide 14. Question 5: Give two boundary shapes that have the same mean and third statistical moment descriptors, but different second moments Question 6: Obtain the grey-level co-occurrence matrix of a 5x5 image composed of a checkerboard of alternating 1’s and 0’s if a) the position operator is defined as “one pixel to the right” and b) “two pixels to the right”. Practical Assignments Question 7: Try the function cad cod that produces the chain code of a connected component in a image. Draw a simple small image, run “cadcod” and check if you agree with the result. Question 8: Try the function splitmerge that implements the split and merge algorithm. Test your program with the binary image from bola.bmp. Visualize what happens when you use different values for the maximum distance. Question 9: Try the function assinaang that produces a signature angle distance to centroid. To test the function, generate a binary image with the form of a square or a circle. Do you agree with the results? Question 10: Read the help of the funcion “regionprops” of MATLAB. Take a satellite image and segment it using the watershed based program shown in a previous chapter. Then compute some form features of the resulting segments. Question 11: Write a function that gets the chain code as produced by the function “cadcod” and generates the corresponding image. Try with the sequence: Chain= [ 0 0 0 7 5 4 4 2 4 2]; Question 12: Read the help of the function fourierdesc that computes the Fourier descriptors and the function invfourierdesc . Verify how the reduction of descriptor Representation and Description affects the shape of an object. Use the function “roipoly” from MATLAB to draw some test images. Question 13: Read how the function invmoment works. Write a MATLAB script that reproduces the same example shown in classroom slides. Question 14: Use the function given here and compute the n first Haralick texture features of each sample of the 5 available types of Brodatz textures. Build 2 dimensional scatter plots for each pair of Haralick features where each texture type is marked with a different color or symbol (see example below). Is there a pair of attributes that could be used to separate these texture types sharply? Hint: use the MATLAB function plot xb ● ● ●● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● xa ● ●