Deep learning for image-based large-flowered chrysanthemum cultivar recognition

Zhilan Liu; Jue Wang; Ye Tian; Silan Dai

doi:10.1186/s13007-019-0532-7

Deep learning for image-based large-flowered chrysanthemum cultivar recognition

Plant Methods. 2019 Dec 4:15:146. doi: 10.1186/s13007-019-0532-7. eCollection 2019.

Authors

Zhilan Liu¹, Jue Wang¹, Ye Tian², Silan Dai¹

Affiliations

¹ 1College of Landscape Architecture, Beijing Forestry University, Beijing, 100083 China.
² 2College of Technology, Beijing Forestry University, Beijing, 100083 China.

Abstract

Background: Cultivar recognition is a basic work in flower production, research, and commercial application. Chinese large-flowered chrysanthemum (Chrysanthemum × morifolium Ramat.) is miraculous because of its high ornamental value and rich cultural deposits. However, the complicated capitulum structure, various floret types and numerous cultivars hinder chrysanthemum cultivar recognition. Here, we explore how deep learning method can be applied to chrysanthemum cultivar recognition.

Results: We propose deep learning models with two networks VGG16 and ResNet50 to recognize large-flowered chrysanthemum. Dataset A comprising 14,000 images for 103 cultivars, and dataset B comprising 197 images from different years were collected. Dataset A was used to train the networks and determine the calibration accuracy (Top-5 rate of above 98%), and dataset B was used to evaluate the model generalization performance (Top-5 rate of above 78%). Moreover, gradient-weighted class activation mapping (Grad-CAM) visualization and feature clustering analysis were used to explore how the deep learning model recognizes chrysanthemum cultivars.

Conclusion: Deep learning method applied to cultivar recognition is a breakthrough in horticultural science with the advantages of strong recognition performance and high recognition speed. Inflorescence edge areas, disc floret areas, inflorescence colour and inflorescence shape may well be the key factors in model decision-making process, which are also critical in human decision-making.

Keywords: Chrysanthemum × morifolium Ramat.; Deep learning; Grad-CAM; Image recognition.