% This is a test program that tests the EZW

% matrix X is an example matrix same as Shapiro's paper given



X=[63 -34 49 10 7 13 -12 7;

   -31 23 14 -13 3 4 6 -1;

   15 14 3 -12 5 -7 3 9;

   -9 -7 -14 8 4 -2 3 2;

   -5 9 -1 47 4 6 -2 2;

   3 0 -3 2 3 -2 0 4;

   2 -3 6 -4 3 6 3 6;

   5 11 5 6 0 3 -4 4];



X0=X;



Y0=max(X);

     Y1=max(Y0); 

     for i=0:12;

        if 2^i<Y1 & 2^i>0.5*Y1;

           threshold=2^i;   % get initial threshold T0;

           break;

        end;

     end;

     

     

     sublist=[];

     [xx,yy]=size(X);

     

     global N

     

     A=mapping(xx);

[m,n]=size(A);

k=1;  N=[]; 

 for k=1:m*n;

     flag=0;

     for i=1:m;

         if flag==1;

             break;

         end

         for j=1:n;

             if A(i,j)==k;

                 N=[N;i,j];

                 flag=1;

                 break;

             end

         end

     end

 end

                 

       order=1;  

while threshold ~= 0.5,  % if threshold~=1, do dominantpass and subordinatepass.

         

   threshold

   

   %Dominant Pass

   

   [D,X,sublist] = dominantpass(X,threshold,sublist); 

   

   DD{order}=D

     

    %Subordinate pass

    

    threshold=threshold/2;

    if threshold ==0.5,

        break;

    end

    

    

   S = subordinatepass(sublist,threshold);

   SS{order}=S

   order=order+1;

    

end



    

    

    

% EZW decoder 



 global N;

 [m,n]=size(N);% the size of initial image

               % m is the pixels of initial image

 XX=zeros(8); % initialize the reconstructured image to zero;

 initialthreshold=32;

 threshold=initialthreshold; % initial theshold ;

 

 sublist=[]; % sublist is the new position matrix 

             % for all significant coefficients 'p' and 'n';

             

             

for k=1:6; % laststeplevel=6; 

                

            RR=zeros(8); % reference matrix RR;

  

     [a,b]=size(DD{k}); % ?    

 

 % dominant pass

 

     i=1; j=1;

     while i<=m;

     

          if j>b; % b is the length of dominant pass vector

             break;

          end

    

          if RR(N(i,1),N(i,2))==1;

              i=i+1;

         

          else

             if DD{k}(j)=='p';

                XX(N(i,1),N(i,2))=threshold;

                RR(N(i,1),N(i,2))=1; %reference matrix =1;

                sublist=[sublist;N(i,1),N(i,2)];

             end

     

             if DD{k}(j)=='n';

                XX(N(i,1),N(i,2))=-threshold;

                RR(N(i,1),N(i,2))=1; %reference matrix =1;

                sublist=[sublist;N(i,1),N(i,2)];

                

             end

         

             if DD{k}(j)=='z';

                 

                RR(N(i,1),N(i,2))=1; %reference matrix =1;

               

             end

     

             if DD{k}(j)=='t';

                RR(N(i,1),N(i,2))=1; %reference matrix =1;

                RR=checkchildren(i,RR);% all zerotree's descendants are set to 1.

               

             end

             

             i=i+1;j=j+1;

      

          end

         

      end

 

 

 % subordinate pass

 

 %[xx,yy]=size(s{k});

 [xx,yy]=size(sublist);

 threshold=threshold/2;

 

   for i=1:xx;

       

       if k==6 |threshold==0.5;

           break;

       end

       

      if SS{k}(i)==1;

         if XX(sublist(i,1),sublist(i,2))>0;

           

            XX(sublist(i,1),sublist(i,2))= XX(sublist(i,1),sublist(i,2))+ threshold;

            

         else 

             

            XX(sublist(i,1),sublist(i,2))= XX(sublist(i,1),sublist(i,2))-threshold;

           

         end



      end

   end

   

  threshold

  k

  XX

end



initialiamge=X0

reconstructuredimage=XX

difference=XX-X0