Lab of COMP 319
Final Project: Image
Compression with MATLAB
Lab tutor : Yao Zhang, Shenghua ZHONG
Email:
zsh696@gmail.com
csshzhong@comp.polyu.edu.hk
Lab 4:
Nov 30, 2011
1
Outline of Lab 4
 Some important reminders of final project
 Some important steps and information of final project
 How to debug the user defined function
2
Important reminders of final project
1. Deadline: Mon Dec. 15 at 23:59pm .
Penalty for late submission
Tue. Dec. 16
Wed. Dec. 17
Thu. Dec. 18
After Dec. 18
•
00:00 - 23:59
00:00 - 23:59
00:00 - 23:59
23:59
25% deduction
50% deduction
75% deduction
Zero point
Please try your best to finish the project and submit
it on time !
3
Important reminders of final project
2. There are only two functions should be and can be
modified and submitted: Compress.m and
Decompress.m.
•
There is no need to submit a final project report.
•
your personal compress.m and decompress.m
functions will be scored by using the uniform
main.m function, so submission of other functions
or files is useless and unallowed.
4
Important reminders of final project
3. You can observe the MSE value and the compression
ratio to check the performance of your functions.
•
The MSE value and compression ratio will be given
above your recovered image, you can check them
according to the grading sample listed on the course’s
webpage.
•
The compression ratio should larger than 1, otherwise
the score of your final project will be zero!
5
Important reminders of final project
4. The components in the matrixes orig_image, comp_image and
reco_image should be the integers.
•
The size of the reco_image should be same with the size
of orig_image.
•
Don't make any modification of the provided functions
expect Compress.m and Decompress.m.
•
Don't read the image file when you
modify Compress.m and Decompress.m, otherwise, you
will get zero point in the final project.
6
How to Debug User-Defined Function
• User-defined functions are stored as M-files. Each must
start with a function definition line that contains





the word “function”,
one or several variables that defines the function output,
a function name, and
one or several variables used for the input argument.
Save the function as M-file using the same name in your function
• Some examples:
• function output = my_function(x)
• function [output1, output2] = my_function(x1,x2,x3)
• Hints: The function name and the names of the input and
output variables are arbitrary and selected by the
programmer, but the word “function” can not be changed.
7
Review of Lab 2 about User-Defined
Function
comments
function output = poly(x)
% This function calculates the value of a third-order
% polynomial
output = 3*x.^3+5*x.^2-2*x+1
Save above commands into an M-file and then type the below
commands in command window to observe the results:
>> a=4;
>> poly(a)
>> b=1:5;
>> poly(b)
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How to Debug User-Defined Function
•
Compress.m, Decompress.m, and xxx.m except main.m are
both user-defined function.
•
They like a black box (user only know the input and output
parameters)
•
Debug is important to check whether the programms are
correct.
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The First Step to Debug User-Defined
Function
Set breakpoint at the line of the Entry to the user-defined function in
the main.m
10
The Second Step to Debug User-Defined
Function
Run main.m to the Entry
11
The Third Step to Debug User-Defined
Function
Click Step in button and go into the user-defined function
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