title: Is there a difference between 8 adjacency and m adjacency of pixels other than its definition?
body: <p>The definition of 8-adjacency and m-adjacency are clear. But is there a case where two pixels p and q can be 8-adjacent, but not m-adjacent. I have given the definition of 8-adjacent and m-adjacent below:</p>
  
  <p><strong>8-adjacency:</strong> two pixels p and q with values from V are 8-adjacent if q is in the set N8(p).</p>
  
  <p><strong>m-adjacency:</strong> two pixels p and q with values from V are m-adjacent if</p>
  
  <p>i) q is in N4(p), OR</p>
  
  <p>ii) q is in ND(p) AND the set N4(p) N4(q) has no pixels whose values are from V.</p>