1000
 0 Citrus *
 900 -( xLeaf
 a Background
 800-

 700-

 600-

 500-
 0- o

 u- 400~ -

 300 o







 0 50 100 150 200 250 300
 Pixel Value

Figure 4-5. Histogram of 25 calibration images in green plane (* indicates 3330 pixels of
 a pixel value of 252 in citrus class).


 1000
 0 Citrus *
 900 a xLa

 800 -1 aBackground

 700 -1 o

 600 -1

 S500-

 LL400~ -

 300-o

 ~o oo
 100 0
 040


 0 50 100 150 200 250 300
 Pixel Value

Figure 4-6. Histogram of 25 calibration images in blue plane (* indicates 33 19 pixels of a
 pixel value of 252 in citrus class).

 As a next step, gray level histograms were plotted in pairs of two color components


and it was found that there existed a clear line of separation between the fruits and the