input plane filter output plane 
Ly 
coherent —_— F ——_f Af 
light 
frequency 
vidicon 
ZZ | 
before 
un equalization 
dr after 
vidicon / 
input output 
information 
. information 
filter 
spectrum information 
  
  
  
  
  
  
  
  
  
  
  
  
  
digital computer greylevel 
  
  
  
Figure 7:  OPTO-ELECTRONIC HYBRID SYSTEM Figure 9:  HISTOGRAM EQUALIZATION, PRINCIPLE OF OPERATION 
  
  
Figure 10: GREY LEVEL REPRESENTATION OF A HOUSING AREA 
a) BEFORE 
} EQUALIZATION 
i b) AFTER 
Figure 8: DENSITY MANIPULATIONS