Drexel University
Department of Electrical and Computer Engineering
ECES 682, Introduction to Image Processing
Spring 2006
Homework 4 Solution
Due May 22, 2006
All problems are from Gonzalez and Woods,
Digital Image Processing
, second edition
Note:
Please submit your results in hard copy (not electronically).
1. Problem 6.5
At the left we have full red, on the right a full blue. In the middle we have (.5 1 .5) = (.5, .5, .5) +
(0 .5 0). This is a mix of mid grey and pure green.
2. 6.6
3. 6.21 The assignment is to obtain a matrix that takes the old RGB values of a pixel and gives
new RGB values with the same luminance (Y) but with U, V values reduced by some factor (for
example, by a factor of 2).
Note: The equations for transforming from RGB to YUV are:
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Answer: Let the above matrix be M. We can obtain the desired matrix by (a) converting from
RGB to YUV by multiplying the RGB components with M, (b) desaturating, by (for example)
multiplying Y by 1, U by 0.5, and V by 0.5, and (c) converting back to RGB by multiplying with
M
1
. The resulting equation equations are:
1
0.000
1.140
1
0.395 0.581
1
2.032
0.000
!
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 Spring '09
 Dand
 Image processing, Computer Graphics, Color space, old RGB values

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