Image compression using Huffman coding

Hi, I need a matlab code for png image compression using Huffman coding, i use this coding but i can't get cmpression, can anynone check my code plase and tell me what is wrong with my coding, also i need to save this to binary file for comparison thank you in advance

clear all;

clc;

% input image

image = imread('img1.png');

[m,n] = size(image);

J = imresize(image,[256 256]);

[x,y] = size(J);

figure();

imshow(J);

title('original RGB image')

drawnow();

Image = rgb2gray(J);

figure();

imshow(Image);

title('original image as grayscale');

drawnow();

[N, M] = size(Image);

Count = zeros(256,1);

for i = 1:N

for j = 1:M

Count(Image(i,j)+1) = Count(Image(i,j)+1)+1;

end

end

prob = Count/(M*N);

prob_1=prob(:)';

symbols = 0:255;

[dict,avglen] = huffmandict(symbols,prob);

comp = huffmanenco(Image(:),dict);

l_encoded=length(comp);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

head1 = [l_encoded [N, M] prob_1 ];

l_head = length( head1 );

header = [l_head head1];

%%%%%%%%%%% File writing %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

image=input('comp.bin): ', 's');

fid=fopen(image,'w');

fwrite(fid, header, 'double'); %%%% writing the header in double format

fwrite(fid,comp,'ubit1'); %%%% writing the encoded bits in binary format after the header

fclose(fid);

decomp = cast( reshape(huffmandeco(comp,dict), N, M), class(Image));

figure();

imshow(decomp);

title('reconstructed image');

drawnow();

figure();

dimg = imsubtract(Image, decomp);

imshow(dimg, []);

title('difference between original and reconstructed (expect no difference)');

drawnow();