Texture-based Fruit Detection via Images using the Smooth Patterns on the Fruit

Abstract

This paper describes a keypoint detection algorithm to accurately detect round fruits in high resolution imagery. The significant challenge associated with round fruits such as grapes and apples is that the surface is smooth and lacks definition and contrasting features, the contours of the fruit may be partially occluded, and the color of the fruit often blends with background foliage. We propose a fruit detection algorithm that utilizes the gradual variation of intensity and gradient orientation on the surface of the fruit. Candidate fruit locations, or “seed points” are tested for both monotonically decreasing intensity and gradient orientation profiles. Candidate fruit locations that pass the initial filter are classified using modified histogram of oriented gradients combined with a pairwise intensity comparison texture descriptor and random forest classifier. We analyse the performance of the fruit detection algorithm on image datasets of grapes and apples using human labeled images as ground truth. Our method to detect candidate fruit locations is scale invariant, robust to partial occlusions and more accurate than existing methods. We achieve overall F1 accuracy score of 0.82 for grapes and 0.80 for apples. We demonstrate our method is more accurate than existing methods.