Clarifications and tips for Homework #1 --------------------------------------- The due date for Homework #1 has been changed. It is now due FRIDAY, APRIL 21. Problem 1c: The answer to this could be argued as *either* true *or* false. The key in answering this question is justifying your position. Problem 1e and 1g: You should be thinking of RGB and HSV as somewhat abstract color spaces -- i.e., ways of "naming" (or "enumerating") a perceived color. RGB does, of course, have a physical realization as voltages that drive electron guns that send electrons to phosphors that emit spectra. In this case, think of RGB as corresponding not to those spectra, but to the perception of color that they cause. Problem 2b: The filters are to be treated "as is". You are not to sum the filter weights and divide. Just analyze the problem using the weights exactly as given. Problem 2c: The output image gets created from the input image by stepping through (x,y) coordinates of the output image, and then figuring out which pixels (X,Y) need to be plucked from the input image. Another way to phrase this is that g(x,y) = f(X(x,y),Y(x,y)), where f is the input image and g is the output image. Recall in class that things happen in a perhaps unexpected way when you do this. When we said g(x,y) = f(2x, 2y), the output image actually *shrank* by 1/2 in x and y. When thinking about coordinate systems, place the origin at the center of the image. Also, we had a sign error in the program that generated the image pairs. We corrected the error, and we also changed one of the images (IV) a little to make it easier to understand what was going on. The new images are in place on the homework web page in both Word and PDF form. You can look at these for reference or you can print the pages and attach them to your homework. In the end, we will just be checking to see which equation number you assigned to each Roman numeral image pair. Problem 3a: The A, B, C spectra basically have nothing to do with the spectra with similar names on the 3rd and 4th pages of your color lecture notes -- it's just a coincidence. You could just as easily rename the spectra in this problem u,v,w. Also, the first plot in this problem shows the sensitivities of the s and l cones, so there are really two functions on that plot. All other spectral plots are single functions (that go to zero in places).