Machine Vision Based on Optical Properties of Biomaterials for Fruit Grading System

It is known that biomaterials have unique characteristics in their color, shape, size, spectral reflectance, and biological structure which are different from industrial materials. Specific machine vision designs are often required for constructing inspection, monitoring, measuring, or production systems to handle the biomaterials. In this presentation, cuticular layers on fruit surfaces are in focus and a direct lighting device with a polarizing filter, which was developed for a fruit inspection system is introduced, because illumination is one of the most important components. Since the biomaterials have various reflectance in different wavelength bands, characteristics of light from gamma ray to terahertz were described. In the visible region, there are many types of light sources, which have different properties on luminance, lumen maintenance, color rendering, color temperature, life, and cost. A high quality image acquisition requires a proper light source selection. Fruit grading facilities are places where the largest number of machine vision systems are practically used in agricultural fields. In this paper, a conventional fruit grading machine and a fruit grading robot with machine visions are introduced. In addition, a contribution of the imaging technologies of the grading systems to the food traceability system is explained.

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