How to compress an color image using Huffman compression in matlab?

How to compress an color image using Huffman compression and also how to decompress it using Huffman decompression in matlab?

[Anushka]

As I am new to matlab can any one please help me?

[Avinash Macharla]

filename = input('enter the image file name', 's');
string = imread(filename);
string = string(:); %input string
symbol=[]; %initialise variables
count=[];
j=1;
%------------------------------------------loop to separate symbols and how many times they occur for i=1:length(string)
flag=0;
flag=ismember(symbol,string(i)); %symbols
    if sum(flag)==0

    symbol(j) = string(i);

    k=ismember(string,string(i));

    c=sum(k);                         %no of times it occurs

    count(j) = c;

    j=j+1;

    end
end
ent=0;
total=sum(count); %total no of symbols
prob=[];
%-----------------------------------------for loop to find probability and %entropy
for i=1:1:size((count)');
prob(i)=count(i)/total;
ent=ent-prob(i)*log2(prob(i));
end
var=0;
%-----------------------------------------function to create dictionary [dict avglen]=huffmandict(symbol,prob);
% print the dictionary.
       temp = dict;

       for i = 1:length(temp)

       temp{i,2} = num2str(temp{i,2});

       var=var+(length(dict{i,2})-avglen)^2;  %variance calculation

       end

       temp
%-----------------------------------------encoder and decoder functions
sig_encoded=huffmanenco(string,dict)
deco=huffmandeco(sig_encoded,dict);
equal = isequal(string,deco)
%-----------------------------------------decoded string and output %variables
str ='';
for i=1:length(deco)
str= strcat(str,deco(i));
end
disp('**str**')
str
disp('**ent**')
ent
disp('**avglen**')
avglen
disp('**var**')
var

Answer 1

[Walter Roberson]

reshape() the content of the image into a vector. Then use Huffman encoding on the vector.

When decoding, decode the encoding data into a vector and reshape() the vector into a 3D array.

[Anushka]

But can you please give me the code for compression and decompression using Huffman codes.

[merr LAMINe]

Where is the benefit after encoding followed by decoding Huffman !. Decoding will produce the same encoded vector .

[Walter Roberson]

Well, you certainly hope that it produces the same vector, but you might have an error in your encoding process or in your decoding process.

It is common for people not to realize that the point of huffman encoding is to be able to create bit vectors with the encoded values, one bit per element, rather than 1 double per element as is returned by the MATLAB huffman encoding routine.

[Bhaumik chaudhari]

can you send me the code my email id:[e-mail]

[Walter Roberson]

The code for exactly what, Bhaumik chaudhari ? Do you need to be able to do Huffman encoding on CT reconstructions read in from DICOM files?