Flood filling algorithm stop condition

I've written an algorithm to compute a flood fill operation that finds all pixels which match the brightness of a seed pixel within a given tolerance. The goal of the algorithm is to follow this flow chart, and stop when the 'foreground queue' is empty. Here is the code I have written so far, it can succesfully find the adaptive neighborhood, but I'm having trouble finding a way to make it stop once every possible pixel has been checked.

%%LANHE

clear
clc

tol=10;



img=double(imread('cameraman.tif'));
%img=imresize(img,.25);

seed=32640;
%seed=2016;

img=padarray(img,[1 1],1);
[m,n]=size(img);

M=size(img,1);

neighbor_offsets =[M, M+1, 1, -M+1, -M, -M-1, -1, M-1];

foreground_queue=seed;
background_queue=0;

iterations=0;

while iterations<155 %~isempty(foreground_queue)
    
    for i=1:length(foreground_queue)
        
        test_pixel=foreground_queue(i); %top pixel off queue
        diff=abs(img(seed)-img(test_pixel));
        

        if diff<=tol %if foreground
            foreground_queue_test{i} = bsxfun(@plus, test_pixel, neighbor_offsets);
            foreground_pass{i}=test_pixel;
            
         
        end
        
        if diff>tol %if background
            background_queue=[background_queue test_pixel];
        end 
       
    end
    
    foreground_passmat=horzcat(foreground_pass{:});
    foreground_passmat(foreground_passmat==seed)=[]; 
    foreground_queue=unique(horzcat(foreground_queue_test{:}));
    
    
    
    %foreground_queue=setdiff(foreground_queue,foreground_passmat);
    iterations=iterations+1;
    
    l(iterations)=length(foreground_queue);
end

length(foreground_passmat)



background_queue(background_queue==0)=[];


figure()
hold on
[j,i]=ind2sub([m,n],foreground_passmat);
[j1,i1]=ind2sub([m,n],background_queue);
plot(i,-j,'*')
plot(i1,-j1,'*')

figure(2)
plot(l)

Answer 1

[Navya Seelam]

Hi,

You can count the total number of pixels checked by the sum of lengths of foreground_queue and background_queue. Once the sum is greater than the total number of pixels use “break” statement to break the loop.