%Read Image
A = imread('test1.jpg');
%to Double
A=im2double(A);
%Get Each Channel
redChannel = A(:, :, 1);
greenChannel=A(:,:,2);
blueChannel=A(:,:,3);
%Loop through the image
for i=1:size(A,1)
 for j=1:size(A,2)
  %get the pixel 3 values
red = double(redChannel(i,j));
green = double(greenChannel(i,j));
blue = double(blueChannel(i,j));
%|------|--------|
%| A    |  C     |
%| B    |  X     |
%|      |        |
%|---------------|
%we want to get predicative value for x ,if we r in the first row we will use the equation that x=A
%if we are in the first column ,we use the equation that x=B
%else we use the equation that x=(A+b)/2;

%check if we r in the first pixel,we will use X=X
if (i==1)&&(j==1)
        red=double(redChannel(i,j));
        green = double(greenChannel(i,j));
        blue = double(blueChannel(i,j));
%check if we r in the first row,we will use X=A
elseif i==1
        red=double(redChannel(i,j-1));
        green = double(greenChannel(i,j-1));
        blue = double(blueChannel(i,j-1));
%check if we r in the first row,we will use X=B
elseif j==1
        red=double(redChannel(i-1,j));
        green = double(greenChannel(i-1,j));
        blue = double(blueChannel(i-1,j));
%Else we will use the equation ,we will use X=(A+B)/2;
else
        red1=double(redChannel(i,j-1));
        red2=double(redChannel(i-1,j));
        green1=double(greenChannel(i,j-1));
        green2=double(greenChannel(i-1,j));
        blue1=double(blueChannel(i,j-1));
        blue2=double(blueChannel(i-1,j));
        red=(red1+red2)/2;
        green=(green1+green2)/2;
        blue=(blue1+blue2)/2;
end
redChannel(i,j)=uint8(red);
blueChannel(i,j)=uint8(blue);
greenChannel(i,j)=uint8(green);
 end
end
%Now we need to get the difference between the original image and predicative image
redChannel2 = A(:, :, 1);
greenChannel2=A(:,:,2);
blueChannel2=A(:,:,3);
for i=1:size(A,1)
 for j=1:size(A,2)
  %get difference between each pixel
   diff1=double(redChannel2(i,j))-(double(redChannel(i,j)));
   diff2=double(greenChannel2(i,j))-(double(greenChannel(i,j)));
   diff3=double(blueChannel2(i,j))-(double(blueChannel(i,j)));
   %Edit the channels with the difference.
   redChannel2(i,j)=uint8(diff1);
   greenChannel2(i,j)=uint8(diff2);
   blueChannel2(i,j)=uint8(diff3);
 end
 end
 %Edit the original image with difference values to work on HUFFMAN on it.
A(:,:,1)=redChannel2;
A(:,:,2)=greenChannel2;
A(:,:,3)=blueChannel2;
imwrite(A,'test1.jpg');
%-----------------------------------------------------------------------------------------
 %read image
imhuff=imread('test1.jpg');
imhuff=double(imhuff);

frequency=zeros(1,511);
 for i=1:size(imhuff,1)
for j=1:size(imhuff,2)
frequency(imhuff(i,j)+256)=(frequency(imhuff(i,j)+256))+1;
end
end

%get probabilities
probabilities=frequency/sum(frequency);


 %loop through all probabilities and form codeword for each probabilities
for index = 1:length(probabilities)
%create empty codeword for each probabilities
    codewords{index} = [];
 %create set from each probabilities containing eachself as start.
    set_contents{index} = index;
 %probabilities for each index
  set_probabilities(index) = probabilities(index);
end

%loop till we have only one set that contain all codewords
while length(set_contents) > 1
 %sort return the sorted array(temp) and the index array(sorted_indicies)
[temp, sorted_indices] = sort(set_probabilities);
%zero set contain the set with the least probabilites
 zero_set = set_contents{sorted_indices(1)};
%zero probability has the probabilities of the least set
 zero_probability = set_probabilities(sorted_indices(1));


for codeword_index = 1:length(zero_set)
codewords{zero_set(codeword_index)} = [0,codewords{zero_set(codeword_index)}];

    end




    one_set = set_contents{sorted_indices(2)};

    one_probability = set_probabilities(sorted_indices(2));



    for codeword_index = 1:length(one_set)

        codewords{one_set(codeword_index)} = [codewords{one_set(codeword_index)},1];
    end



    set_contents(sorted_indices(1:2)) = [];

    set_contents{length(set_contents)+1} = [zero_set, one_set];


    set_probabilities(sorted_indices(1:2)) = [];

    set_probabilities(length(set_probabilities)+1) = zero_probability + one_probability;

end



for index = 1:length(codewords)
    disp([num2str(index), '    ', num2str(probabilities(index)),'    ',num2str(codewords{index}(length(codewords{index}):-1:1))]);
end
[h,w] = size(dec2bin(redChannel2));
before = h*w
av_length = 0;
for index = 1:length(codewords)
    av_length = av_length + length(codewords{index});
end
av_length

disp(['The Huffman coding rate is:                ',num2str(before/av_length)]);