COMP4421 Matlab 代做、代写MATLAB、代做CANVAS 代写Matlab程序语言

日期：2019-12-13 08:16

The Hong Kong University of Science and Technology

Department of Computer Science and Engineering

COMP4421 (Fall 2019)

Assignment 3

Total = 100 marks

Due: 11:55pm, Dec 9, 2019

Assignments must be submitted via CANVAS

Late Policy: 10% reduction; only one day late is allowed, i.e. 11:55pm, Dec 10

Overview

This assignment consists of two sections: programming section and written section.

Both programming and written parts should be submitted via the CANVAS system. If

you would like to finish the written assignment with hand writing, you may scan and

upload it as a PDF file.

Programming assignment specifics (60%)

Pre-requirement

2.1.1 Input: The input images are in the folder “input_imgs” (/Sample/input_imgs).

You should test all the input images and paste the result images in the PDF file. Note

that we will have some other test images for grading.

2.1.2 Language: Matlab/Octave.

2.1.3 Functions to be used: In this assignment, you can use the built-in function for

filtering and edge detection. However, you cannot use any built-in functions

relating to the image warping and segmentation. 1/6

Programming question 1 - Image Warping (40%)

Based on the 4 corner points computed in Assignment 2, apply the image warping to

transform the target A4 paper into a standard A4 form, that is, 210? ? 297? for

vertical direction and 297? ? 210? for horizontal direction, where ? is the

parameter decided by the user. Inside your own image warping function, you also

need implement your own bilinear interpolation. Please describe your image

warping algorithm briefly in the PDF file.

The function prototype is given in the image_warping.m. If you cannot obtain the 4 corner points in Assignment 2, you can manually find the 4

corner points using some tools in Matlab/Octave.

A sample output is provided as follows,

Programming question 2 - Digit Segmentation (20%)

Followed by the Task 2.1, our input images in this task are the transformed A4 paper

with some hand-written digits on it. Your task here is to use a certain segmentation

algorithm to segment each digit. Note that you can choose any segmentation

methods. However, no matter which algorithm you choose to use, you should

implement it by yourself. Please describe your segmentation algorithm briefly in the

PDF file.

The function prototype is given in the digit_segment.m.

A sample output is provided as follows,

2/6

Here, I provide one of the algorithms I used in my program for the digit

segmentation.

Step 1: Threshold the input images to obtain binary images;

Step 2: Horizontal projection. Count the number of white pixels along horizontal

direction. The number of rows for the digits should be equal to the number of peaks

in the projected histogram. We can then segment the digits by rows.

Step 3: Vertical projection. For each row, we count the number of white pixels along

vertical direction. The number of columns for the digits should be equal to the

number of peaks in the projected histogram. We can then segment the digits by

columns.

[Note: for step 3 you may face the problem that some digits cannot be separated

properly. Here is another idea for Step 3. Scan each column and count the number of

black pixels, denoted as N. If N > H – n, where H is the height of the row_image

obtained in Step 2 and n is a parameter defined by user, the column will be marked.

The segmentation will be performed based on the marked column. This idea, which is

similar to vertical projection, compares the height of the row_image and thus is

easier to control.]

I provide the pipeline combining Assignment 2 and Assignment 3 as follows. Note

that only the parts in the orange dash box are required in this assignment.

3/6

4/6

Written assignment specifics (40%)

Written question 1 - Image Transformation

There is an image I shown as follows. The transformation is defined as ?(??) ≡ ????,

where ?? = 2? ? ? ?7 and ?? = 2??7. After the transformation using ?, point A, B, C and

D are transformed to point E, F, G and H respectively.

(Hint: For a 2x2 matrix ? = 2? ? ? ?7, the matrix inverse is ?:; = ;

<=:>? 2 ? ?? ?? ? 7.)

1a) Find the transformation matrix ??. Please show all your steps clearly.

Suppose the intensity values of point I, K, L and M are 2, 5, 9 and 15 respectively.

Image I

Image I’ x y

5/6

1b) Find the intensity value of point J using Bilinear Interpolation. Please show

all your steps clearly.

Written question 2 - Quantization

Given a 4x4 gray-level image A as follows:

13 115 24 231

128 200 64 55

55 255 74 35

178 29 1 80

2a) Compute the quantization (uniform quantization) of A from 256 levels (8 bits) to

16 levels (4 bits).

2b) Compute the column-wise improved gray-scale (IGS) quantization of A from 256

levels (8 bits) to 16 levels (4 bits).

2c) Find the root-mean-square error and mean square signal-to-noise ratio of the result

from your answers in 2a) and 2b).

Image I’

Image I x y

6/6

Written question 3 – Huffman coding

Given Huffman code in the below table.

Symbol Code

C 01

E 10

M 00

O 110

P 1111

R 11101

T 111000

U 111001

3a) Decode the encoded string “011100011111110011110001011101” with the given

Huffman code.

3b) Compute the Huffman code for each symbol in the words “image processing” and

fill in the following table. Show your steps clearly.

Symbol Code

acegimnoprs