perform an erode on this with a 3x3 box of 1's
  
    0   0   0   0   0   0   0   0   0   0
    0   0 255 255 255 255 255 255 255   0
    0   0 255 255 255 255 255 255 255   0
    0   0 255 255 255 255 255 255   0   0
    0   0   0   0   0 255 255 255   0   0
    0   0   0   0   0 255 255 255 255   0
    0   0   0   0   0 255 255 255 255   0        
    0   0   0   0   0 255 255 255 255   0    
    0   0   0   0   0   0   0   0   0   0
    0   0   0   0   0   0   0   0   0   0
    
 perform a dilate on this with a 3x3 box of 1's
  
    0   0   0   0   0   0   0   0   0   0
    0   0 255 255 255 255 255 255 255   0
    0   0 255 255 255 255 255 255 255   0
    0   0 255 255 255 255 255 255   0   0
    0   0   0   0   0 255 255 255   0   0
    0   0   0   0   0 255 255 255 255   0
    0   0   0   0   0 255 255 255 255   0        
    0   0   0   0   0 255 255 255 255   0    
    0   0   0   0   0   0   0   0   0   0
    0   0   0   0   0   0   0   0   0   0    

      
 ======
    

Connected components algorithm on this:

    0   0   0   0   0   0   0   0   0   0
    0   0   0   0 255 255 255 255 255   0
    0   0 255 255 255 255 255 255 255   0
    0   0 255 255 255   0   0   0   0   0
    0   0   0   0   0   0   0   0   0   0
    0 255 255   0   0 255 255   0 255   0
    0 255 255   0   0 255 255   0 255   0        
    0 255 255   0   0 255 255   0 255   0    
    0 255 255 255 255 255 255   0   0   0
    0 255 255 255 255 255 255   0   0   0
    0   0   0   0   0   0   0   0   0   0
 
region with label 3 (the U shaped region)
     compute: area, centroid, perimeter (4-adjacency), 
     perimeter length 
     Consider the origin to be at top left pixel, increases to right for column 
     numbers (0 to 9) and increases down for row numbers (0 to 10)
     
     
suppose three histograms:
normalize them and then
determine which of the h2 or h3 is closer to h1 using L1 distance

h1:  150 165 275 300  10   0 200 400
h2:   90 140 175  10 100  85  50 350
h3:  400 450 300   0   0   0   0   0