Another important parameter that may affect the result
of the adaptive segmentation procedure is the size of the
M×M operational sub-images. For the current configuration
of the X-ray scanning system, we most frequently used
the 32×32 operational sub-images for adaptive thresholding.
Changing the size of the operational sub-image may
lead to different results in some cases. The binary images
of guava shown in Fig. 11a and b are the results of adaptive
thresholding using different sub-image size of 32×32
and 12×12, respectively. It is clear that the sub-image size
affected the size distribution of the segmented spots. This
result subsequently affected the detection of the infestation
sites when the morphological filtering is applied. In Fig. 11c, a
shadow region corresponding to the core of the guava fruit
exists in the middle part of the X-ray image. This region,
with similar size to the infestation site, was misclassified
as an infestation site using 32×32 operational sub-images.
Using 12×12 operational sub-images in adaptive thresholding,
finer spots were obtained and the misclassified region in
Fig. 11c was screened