ECE 5256 Test 2 Spring 2021
ECE 5256 Test 2 Spring 2021
1(4) What is the geometric mean of the following values: 4, 7, 20?
(4*7*20)^1/3 = 8.24
2(4) What is the harmonic mean of the following values: 100, 100, 50?
3/(1/100 + 1/100 + 1/50) = 75
3(2) An image undergoes uniform linear motion in at angle of 45 degrees with respect to the horizontal for a time T√2. Would you get the same result if the motion was in the horizontal direction for time T, then in the vertical direction for time T?
No – turns out to be someone difficult to get a definitive answer. Gave full credit to both responses
4(4) Given an image with a power spectrum equal to sin(f) corrupted with additive noise with a constant power spectrum of 0.25, what is the value of the Wiener filter at f = pi/2?
1/(1+0.25) = 0.8
5(3) Given a 256 x 256 pixel image, if a projection is taken every 1 degree in a complete circle, how many rows will there be in the sinogram where the sinogram is x l (vertical x horizontal).
360
6 (4) Given a 256 x 256 pixel image, if a projection is taken every 1 degree in a complete circle, how many columns will there be in the sinogram where the sinogram is x l (vertical x horizontal).
256sqrt(2) = 362.03 (362 to 363 acceptable)
7(4) Given a 256 x 256 image that consists of a vertical line, what will be its Radon transform (,l)? Could get different answers depending on coordinate system. Gave full credit except for last two answers.
A point at 90,0
A point at 90,128
A point at 0,128
A sinusoid
A horizontal line
8(3) When creating a backprojection image from the Radon transform, the image should be:
High-pass filtered
Low-pass filtered
Doesn’t have to be filtered
9(4) For length 256 length signal, how many wavelet coefficients are generated at the level of a wavelet transform?
128
10(4) For length 256 length signal, how many wavelet coefficients are generated at the 2nd level of a wavelet transform?
64
11(4) For a 256 x 256 pixel image, how many basis functions are there for a wavelet transform?
256 x 256 = 65,536
2021-04-07