A Double Image Acquisition System with Visible and UV LEDs for Citrus Fruit

Abstract

There are many types of citrus fruit grading machine with machine vision capability. While most of them sort fruit by size, shape and color, detection of fruit rot remains challenging because their colors are similar with normal parts. Objectives of this research were to investigate if fluorescence would be a good indicator of the fruit rot, and to develop an economical solution to add the rot inspection capability to an existing machine vision fruit inspection station. A machine vision system consisting of a pair of white and UV LED lighting devices and a color CCD camera was proposed for the orange fruit grading task. Since the time lag between the color and fluorescence image captures was short (14 ms), it was possible to inspect color, shape, size, and rot of a fruit on the move before it leaves an existing industrial inspection chamber.