My first Matlab Program, Encode and Decode image using Huffman Coding

For the academic purpose i had written a small program in Matlab.

I have tried encoding and decoding the image by using Huffman coding.

Huffman code generally used for data encoding but i tried Huffman coding on small image.

Preconditions:

1. You need to create a small image, in my code i am using PSR.jpg
2. It will work well only with small images

Matlab Code:

%Huffman Coding on image by Suresh Raju Pilli

%clearing all variableas and screen
clear all;
close all;
clc;

%Reading image
a=imread('psr.JPG');
figure,imshow(a)

%converting an image to grayscale
I=rgb2gray(a);

%size of the image
[m,n]=size(I);
Totalcount=m*n;

%variables using to find the probability
cnt=1;
sigma=0;

%computing the cumulative probability.
for i=0:255
k=I==i;
count(cnt)=sum(k(:))

%pro array is having the probabilities
pro(cnt)=count(cnt)/Totalcount;
sigma=sigma+pro(cnt);
cumpro(cnt)=sigma;
cnt=cnt+1;
end;


%Symbols for an image
symbols = [0:255];

%Huffman code Dictionary
dict = huffmandict(symbols,pro);

%function which converts array to vector
vec_size = 1;
for p = 1:m
for q = 1:n
newvec(vec_size) = I(p,q);
vec_size = vec_size+1;
end
end

%Huffman Encodig
hcode = huffmanenco(newvec,dict);

%Huffman Decoding
dhsig1 = huffmandeco(hcode,dict);

%convertign dhsig1 double to dhsig uint8
dhsig = uint8(dhsig1);

%vector to array conversion
dec_row=sqrt(length(dhsig));
dec_col=dec_row;

%variables using to convert vector 2 array
arr_row = 1;
arr_col = 1;
vec_si = 1;

for x = 1:m
for y = 1:n
back(x,y)=dhsig(vec_si);
arr_col = arr_col+1;
vec_si = vec_si + 1;
end
arr_row = arr_row+1;
end


%converting image from grayscale to rgb
[deco, map] = gray2ind(back,256);
RGB = ind2rgb(deco,map);
imwrite(RGB,'decoded.JPG');

%end of the huffman coding

Postcondition:

1. Check the original image and decoded image
2. Analyze the compression ratio.

You can easily understand the code. Its not at all difficult.

Please send your feedback and comments to psrdotcom@gmail.com