I tried this: 
flamefront = [];
for c = 1:size(mean_max_upper)
    r = 1;
    indicator = 0;
    while indicator == 0;
        if mean_max_upper(r,c) >= .25*max(mean_max_upper(r,c));
            indicator = 1;
            flamefront = [flamefront; r,c];
        end
        r = r+1;
    end
end 
where mean_max_upper is the image and flamefront is the array I would like to fill. However it's  just running from 1 to the amount of rows and not saving anything. 


