Diameter measurement method for immature apple based on watershed and convex hull theory

In agriculture field, the knowledge about the size of immature fruit in its growing period could be helpful to the aspects such as precision fertilization and irrigation, training and pruning, yield estimation and harvest stage determination. Thus, it can improve the fruit yield and quality. The color of fruits on tree is very similar with their surrounding objects, so that the recognition and size calculation is very difficult in natural condition. This paper proposed an algorithm of diameter measurement for immature apple based on the morphological reconstruction, the watershed and convex hull theory. The experiment results showed that the minimum root mean square error (RMSE) and the mean value were 1.91 mm and 2.27 mm, respectively. In conclusion, the paper proposed a new approach to deal with segmentation for overlapping and occluded apples and to realize size detection and precise measurement of immature fruits in natural condition. And the results were consistent with the manual measurement, which coul