EE5356 Digital Image Processing
Instructor: Dr. K.R. Rao
Spring 2011, Final Exam
Tuesday, May 10, 2011
2:00 – 3:30 PM (1 hour and 30 minutes)
(CLOSED BOOK, CLOSED NOTES)
INSTRUCTIONS:
1. Closed books and closed notes.
2. Please show all the steps in your works.
4. You can work problems in any order.
At the end please rearrange in the correct order.
5. Please print your name and student ID.
6. No cheating, no talking.
Name_______________________________________
Student ID ___________________________________
Note:
A) Please draw a line to separate answers to different questions.
B) Figures must have a title, both axes must be labeled correctly, and ticks marked where needed.
1. [5 points] Distinguish clearly between image restoration and image enhancement.
2. [5 points] What is an (a) inverse filter (b) pseudo-inverse filter?
3. [5 points] What is a Wiener filter?
4. [5 points] Compare pseudo-inverse filter with Wiener filter.
5. [5 points] What is power spectral density (PSD)?
6. [5 points] How is PSD related to autocorrelation/autocovariance of a sequence?
7. [5 points] What is a geometric mean filter (GMF). What are its advantages and disadvantages?
8. [5 points]
Give an example of a non-linear filter. Why is it called a non-linear filter?
9. [5 points] What is a constrained least squares filter (CLSF)? Also give its advantages and
disadvantages.
10. [5 points] Geometric mean filter is given by:
=(pseudo-inverse filter)s(Wiener filter)1-s
when s0, GMF?
when s1, GMF?
11. [10 points] Define:
a. Entropy
b. Huffman coding
c. Run-length coding
d. Transform coding
e. Predictive coding
12. The block diagram representing DPCM, is shown below.
+
+
u (n)
-
e(n)
Q
e  (n)
e  (n)

+
u (n)
+
P
+
+
+
+
u  (n)
u  (n)
P
u  (n)
Encoder
Decoder
a. [4 points] Define linear predictor and causal predictor.
b. [5 points] Define adaptive DPCM, Quantization error (QE), Reconstruction error(RE).
Show that QE = RE.
13. [8 points] A feed forward predictor is shown below:
Feedforward predictor.
Identify which one is lossless (a) or (b), and why?
Identify which one is lossy (a) or (b), and why?
Why is this called feedforward predictor?
14. [9 points] In transform coding, define:
f. geometrical zonal sampling
g. maximum variance zonal sampling
h. threshold sampling
15. [7 points] Consider the following block diagram for a system used for evaluating transmission errors:
What are the roles of digital leak and clip? Sketch the decoder block diagram.
16. [7 points] A double predictor DPCM encoder is shown below.
Explain its role. Sketch the block diagram for the decoder. Identify all the parameters. F and H are
predictors.