1. 1 Computational Vision CSCI 363, Fall 2012 Lecture 12 Review for Exam 1

2. 2 Review questions Possible questions on exam: 1)List the levels of analysis involved in Marr's approach to vision. Briefly explain each one. 2)List the major parts of a neuron and their functions. 3)Describe the events that occur during action potential generation. 4)Describe the events that occur in neural signaling.

3. 3 Problem 1. a) Compute the 2D convolution of the following image and operator. Place the result in the square corresponding to the lower right square of the operator. b) What operation does the operator perform? What can the convolution tell you about the image?

4. 4 Problem 2. a)A cell in the primary visual cortex gives the following responses when tested with moving bars of light. (This will be diagrammed in class) How would this cell be classified according to Hubel and Wiesel's system of classification for V1 cells? b) What kinds of information might this cell be involved in computing?

5. 5 Problem 3. Write a matlab function, colorNumbers = countColorPixels(image), that returns a three component vector that has the number of pixels in image that contain red, the number that contain green and the number that contain blue. (Note that some pixels may contain more than one color).

6. 6 Problem 4. a) Using the pinhole camera model of the eye's projection system, calculate the projected y positions of the top and bottom of the following image. Diagram the projection system. (-1, 4) (2, 5) Y Z Image plane 1 b) How would your calculation change if the image plane were a distance of 2 units behind the origin?

7. 7 Possible questions The following questions could appear on the exam. (There may also be questions that are not listed here). 1)What is the optic chiasm? What is its purpose? 2)What are the 2 major processing streams in the cortex? What are their functions? 3)What are the 5 major cell types in the retina? 4)What are the steps involved in Marr and Hildreth's edge detection algorithm? What is the purpose of each of these steps? 5) Diagram Barlow and Levick's direction selective circuit. Explain how it works.

8. 8 Even more possible questions 6) What are ocular dominance (or orientation) columns? What are blobs? What is a hypercolumn? What do you think the purpose of a hypercolumn is? 7) Describe the center/surround responses in retinal ganglion cells? 8) How do the center-surround cells in the retina relate to Marr's edge detection algorithm? 9) Why is vision considered an ill-posed problem? How does the visual system deal with this? 10) What is the principal visual pathway from retina to extra- striate cortex?