One of the most practical and successful techniques for nondestructive
quality evaluation and sorting of agricultural products is
the electro-optical technique, which judges the optical properties
of the product (Chen, 1996). This technique – which can be used
to detect color uniformity, shape, size, external defects, foreignmaterials, and disease – has been used for post-harvest grading for
a wide variety of agricultural products. According to Jayas and
Karunakaran (2005), a machine vision system is a nondestructive,
objective, rapid, and cost effective technique that determines the
external and internal characteristics of products, including maturity,
ripeness, bruises, defects, moisture, and nutrients. They say
the method not only identifies the presence of defects but also
can be used to quantify defects so that only those products which
meet minimum grading requirements will be sorted for consumption.
For these reasons the visible spectrum system measuring
reflectance properties are the most widely adopted forms of technology
in the industry.