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

Question

Anushka 2015-6-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/225580-how-to-compress-an-color-image-using-huffman-compression-in-matlab

评论： Walter Roberson 2020-9-22

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

2 个评论
显示无隐藏无

Anushka 2015-6-27

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

Avinash Macharla 2018-9-23

编辑：Walter Roberson 2019-4-12

在 MATLAB Online 中打开

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