a) 
  
1) GREY LEVEL TRANSITION 
  
  
  
  
  
  
  
2) FIRST DERIVATIVE 
  
  
  
3) SECOND DERIVATIVE 
  
  
c) 
Figure 15: HIGH PASS FILTERING BY A TWO DIMENSIONAL DIFFERENTIATION 
a) FILTER-SUBMATRIX 
b,c) RESULTS OF A HIGH PASS FILTER PROCESS 
b) 
Figure 16: EDGE-ENHANCEMENT (MACH'S PHENOMENON) 
a) PRINCIPLE OF OPERATION 
b) GREY LEVEL INPUT DATA 
¢) ENHANCED IMAGE