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Smart Agriculture ›› 2025, Vol. 7 ›› Issue (1): 124-135.doi: 10.12133/j.smartag.SA202411016

• 专题--农业知识智能服务和智慧无人农场(下) • 上一篇    下一篇

基于实例白化与特征恢复的草莓病害识别领域泛化方法

胡晓波1, 许桃胜2(), 王成军1, 朱洪波1, 甘雷1   

  1. 1. 安徽理工大学 人工智能学院,安徽 淮南 232001,中国
    2. 中国科学院合肥物质科学研究院,安徽 合肥 230031,中国
  • 收稿日期:2024-10-30 出版日期:2025-01-30
  • 基金项目:
    安徽理工大学高层次引进人才科研启动基金(2024yjrc05); 国家自然科学基金(62003001); 安徽理工大学校级重点项目(XCZX2021-01)
  • 作者简介:
    胡晓波,博士,讲师,研究方向为深度学习与农作物病虫害识别等。E-mail:
  • 通信作者:
    许桃胜,博士,副研究员,研究方向为智慧农业、农业大数据和数据挖掘等。E-mail:

Domain Generalization Method of Strawberry Disease Recognition Based on Instance Whitening and Restitution

HU Xiaobo1, XU Taosheng2(), WANG Chengjun1, ZHU Hongbo1, GAN Lei1   

  1. 1. School of Artificial Intelligence, Anhui University of Science and Technology, Huainan 232001, China
    2. Hefei Institutes of Physical Science, Chinese Academy of Science, Hefei 230031, China
  • Received:2024-10-30 Online:2025-01-30
  • Foundation items:Scientific Research Foundation for High-level Talents of Anhui University of Science and Technology(2024yjrc05); National Natural Science Foundation of China(62003001); University-Level Key Projects of Anhui University of Science and Technology(XCZX2021-01)
  • About author:

    HU Xiaobo, E-mail:

  • Corresponding author:
    XU Taosheng, E-mail:

摘要:

【目的/意义】 基于深度神经网络的草莓病害识别模型通常假设训练集(源域)和测试集(目标域)满足独立同分布。然而,在实际应用中由于光照、背景环境和草莓品种等多种因素的影响,测试集与训练集存在领域差异,造成模型在应用过程中的识别精度出现明显下降。针对这一问题,本研究提出一种基于实例白化与特征恢复的领域泛化方法,用于提升草莓病害识别模型的泛化性能。 【方法】 该方法首先利用实例白化技术消除源域和目标域间的风格差异,再从滤除的风格特征中提取任务相关特征,最后将任务相关特征恢复到白化后的特征中,以减轻实例白化对特征类别区分度的影响。为增强从风格特征中分离任务相关特征的效果,设计了两个特征提取器分别提取任务相关和任务无关特征,并采用双段恢复损失约束两特征提取器所提取特征与任务的相关性,引入互信息损失确保特征的相互独立,进一步增强特征分类效果。 【结果和讨论】 该方法可以在不降低源域识别精度的前提下,有效提升各病害识别模型在目标域上的泛化性能,如AlexNet加入该算法后,其不同风格目标域上的识别精度可分别提升3.97个百分点和2.79个百分点。相较于IBN-Net(Instance Batch Normalization Net)、可切换白化(Switchable Whitening, SW)、样式归一化和恢复模块(Style Normalization and Restitution, SNR)等其他领域泛化方法,该算法在测试数据集上的泛化性能可分别提高2.63%、2.35%和1.14%。 【结论】 本方法可有效提升基于深度学习的草莓病害识别模型在目标域中的泛化性能,可为草莓病害精准识别提供可靠的技术支撑。

关键词: 深度神经网络, 草莓病害识别, 实例白化, 特征恢复, 领域泛化

Abstract:

[Objective] Strawberry disease recognition models based on deep neural networks generally assume that the training (source domain) and the test (target domain) datasets are identically and independently distributed. However, in practical applications, due to the influence of illumination, background and strawberry variety, the target domain often exhibits significant domain shift from the source domain. The domain shift result in accuracy decline of the models in target domain. To address this problem, a domain generalization method based on instant whitening and restitution (IWR) was proposed to improve the generalization performance of strawberry disease identification models in this research. [Methods] Samples from different source often exhibit great domain shift due to variations in strawberry varieties, regional climate, and photography methods. Therefore, a dataset was constructed for domain generalization research on strawberry disease using two distinct approaches. The first dataset was acquired using a Nikon D810 camera at multiple strawberry farms in Changfeng county, Anhui province, with a fixed sampling schedule and fixed camera distance. In contrast, the second dataset was an open-source collection, primarily comprising images captured using smartphones in multiple strawberry greenhouses in Korea, with varied and random shooting distances and angles. The IWR module mitigated style variations (e.g., illumination, color) through instance whitening, where features were normalized to reduce domain discrepancies between the datasets. However, such operation was task-ignorant and inevitable removed some task-relevant information, which may be harmful to classification performance of the models. To remedy this, the removed task-relevant features were attempted to recover. Specifically, two modules were designed to extract task-relevant and task-irrelevant feature from the filtered style features, respectively. A dual restitution loss was utilized to constraint the modules' feature correlation between the task and a mutual loss was used to ensure the independence of the features. In addition, a separation optimization strategy was adopted to further enhance the feature separation effect of the two modules. [Results and Discussions] The F1-Score was adopted as evaluation metrics. A series of ablations studies and comparative experiments were conducted to demonstrate the effectiveness of the proposed IWR. The ablation experiments proved that the IWR could effectively eliminate the style variations between different datasets and separate task-relevant feature from the filtered style features, which could simultaneously enhance model generalization and discrimination capabilities. The recognition accuracy increased when IWR pluged to AlexNet, GoogLeNet, ResNet-18, ResNet-50, MobileNetV2 and MobileNetV3. It demonstrated that the proposed IWR was an effective way to improve the generalization of the models. Compared with other domain generalization methods such as IBNNet, SW and SNR, the generalization performance of the proposed algorithm on test datasets could be improved by 2.63%, 2.35% and 1.14%, respectively. To better understand how IWR works, the intermediate feature maps of ResNet-50 without and with IWR were compared. The visualization result showed that the model with IWR was more robust when the image style changed. These results indicated that the proposed IWR achieves high classification accuracy and boosts the generalization performance of the models. [Conclusions] An instance whitening and restitution module was presented, which aimed to learn generalizable and discriminative feature representations for effective domain generalization. The IWR was a plug-and-play module, it could be inserted into existing convolutional networks for strawberry disease recognition. Style normalization and restitution (SNR) reduced the style information through instance whitening operation and then restitutes the task-relevant discriminative features caused by instance whitening. The introduced dual restitution loss and mutual loss further facilitate the separation of task-relevant and task-irrelevant feature. The schemes powered by IWR achieves the state-of-the-art performance on strawberry disease identification.

Key words: deep neural networks, strawberry disease recognition, instant whitening, feature restitution, domain generalization

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