300
 o Citrus x Leaf a Background

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 50


 0 50 100 150 200 250 300
 Red (gray level)
 Figure 4-9. Pixel distribution in 25 calibration images in red-green plane.


 Thresholds shown in Figures 4-7 and 4-8 were used for the binarization step. The

algorithm classified a pixel as citrus fruit if it fell inside the thresholds; otherwise it was

classified as a background class. An example of image processing steps for a typical

citrus grove image is shown in Figure 4-10. This image is used as an example to explain

various steps involved in the implementation of the fruit counting algorithm. Figure

4-10 (a) shows a sample color image in the validation data set. Fruits were extracted by

applying binarization on the sample color image in HSI color plane. The binarized image

is shown in Figure 4-10 (b).

 4.2 Preprocessing

 The binarized images contained noise mainly due to the little overlap of the leaf

class with the citrus class in the hue-saturation color plane. By applying a threshold of