In order to validate the proposed online system, the same
samples were visually re-sorted by 3 experts. They did not
use their sense of touch. The results of the online sorting
system and experts are illustrated in Tables 7 and 8. The comparisons
between human vision and machine vision are given
in Table 9. As it is revealed from Table 9, human vision and
machine vision did not have significant differences except for
the Rotab stage. The principle reason for misclassification of
the Rotab stage is that a Rotab starts to change its skin color
from the top of the fruit down to the perianth (connection
point to the tree), and this color change may have different
intensities on two faces of a fruit (Fig. 11). So results will depend
on which side is in front of the camera. In proposed sorting
system fruits were not rotated in front of the camera,
therefore, some errors occurred in the Rotab samples where
images were captured from the face that had less color change
compared to that of the other face, so they were misclassified
as a Khalal. Also there was an error at the Khalal stage that
was sorted as a Tamar in replication 1. The error occurred
due to rolling of the fruit out of the camera’s field of view
on the conveyor belt; so the back ground image was captured
and after back ground removal, the black image was produced.
Since a pixel value of black was zero, it was recognized as a
Tamar.