Quantitative Decision Method of Appropriate Apple Harvest Time using Color Information

Abstract

In fruit farming, the appropriate time of harvesting high-quality and high-value fruits is determined by comparing the surface color of tree's fruit and a fruit color chart defined for each fruit cultivar. This comparative examination comprises visual inspection by the farmer and a sensory inspection based on sensibility information. Thus, the decision varies across individuals because the decision criterion is not defined quantitatively and is not unified. This study aims to develop a system to determine the appropriate time for harvesting fruit from the tree. In this paper, we used apples to develop a quantitative method for appropriate harvest time. We focused on the HSV and L^*a^*b^* color spaces used by image processing. Consequently, it was found that using the value of H and a^* in deciding on the proper harvest time was useful. We also conducted a comparative analysis of apple growth and color and color differences to investigate our quantitative method for determining appropriate harvest time. These results of the procedure show that quantitatively determining the proper harvesting time of fruit is possible.