function ans = findedge(a)

% M-file call MUST be in form of findedge(img), NOT findegde img !!

sz=size(a);

topcols = 100;
toprows=62;
botcols = sz(2)-100;
botrows = sz(1)-62;

whitetol = 130;
pixels=100;
found=0;
ans = [0 0 0 0];

for i = 1:toprows;
  for j = 1:topcols;
    if (mean( [mean( a(i:i+pixels,j,:) ) , mean( a(i,j:j+pixels,:) ) ] ) < whitetol)
			
       ans(1) = i;
       ans(2) = j;
       found = 1;
       break;
     end;
  end;
  if (found == 1) break;
  end;
end;
if (found == 0) ans=[999 999];
end; 

for m = sz(1): -1: botrows;
	for n = sz(2): -1: botcols;
	  if (mean([ mean( a(m-pixels:m,n,:)) , mean( a(m,n-pixels:n,:)) ]) <whitetol)
	  
	    ans(3) = m;
	    ans(4) = n;
	    found = 2;
	    break;
	    end;
          end;
        if(found==2) break;
        end;
end;
if (found==0)
	ans(3)=999;
	ans(4)=999;
end;