Application of Machine Vision in External Quality Detection and Grading of Citrus in China

External quality of citrus is one of the most important factors which can influence consumer’s purchase and decide their market value.External quality of citrus is generally evaluated by considering their color，size，shape，as well as the visual defects.Manual detection and grading for external quality are very time-consuming，laborious and subjective.Because of the objective and high degree of automation，traditional machine vision and hyperspectral vision have become a hot spot in the research of external quality testing technology and equipment of fruits and vegetables.Research status，challenges and future development directions of machine vision and hyperspectral vision technology in citrus external quality detection technology and equipment in China were reviewed.