Multi-Level Metric Learning Network for Fine-Grained Classification

The application of fine-grained image classification can be problematic due to subtle differences between classes. The existing global feature-based methods have worse accuracies than regional feature-based methods, because regional feature-based methods focus on the determination of differentiated...

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Main Authors: Jiabao Wang, Yang Li, Zhuang Miao, Xun Zhao, Zhang Rui
Format: Article
Language:English
Published: IEEE 2019-01-01
Series:IEEE Access
Subjects:
Online Access:https://ieeexplore.ieee.org/document/8903259/
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author Jiabao Wang
Yang Li
Zhuang Miao
Xun Zhao
Zhang Rui
author_facet Jiabao Wang
Yang Li
Zhuang Miao
Xun Zhao
Zhang Rui
author_sort Jiabao Wang
collection DOAJ
description The application of fine-grained image classification can be problematic due to subtle differences between classes. The existing global feature-based methods have worse accuracies than regional feature-based methods, because regional feature-based methods focus on the determination of differentiated features within local regions. To learn more discriminative global features, in this paper, we proposed the use of L2 normalization to tackle a neglected conflict between the widely used metric loss (triplet loss) and classification loss (softmax loss) in global feature-based methods. Furthermore, a multi-level metric learning network (MMLN) is proposed for fine-grained image classification based on global features. In the MMLN, multi-level metric learning objectives and classification objectives are present at multiple high-level layers. The multi-level metric learning objectives work together to supervise the network in order to learn highly discriminative features. In addition, a new probability aggregation strategy (PAS) is proposed to produce a fused prediction by combining the multi-level predictive probabilities. Experiments were conducted on three standard fine-grained classification datasets (CUB-200-2011, Stanford Cars, and FGVC-Aircraft). Results demonstrated that our MMLN achieved accuracies of 88.0%, 94.6% and 92.4% respectively and outperformed state-of-the-art methods, substantially improving fine-grained classification tasks. Besides, gradient-weighted class activation mapping (Grad-CAM) shows that the MMLN is able to pay more attention to the discriminative local regions due to the application of multi-level metric learning.
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spelling doaj.art-aee958a1cf1c4867810ccbf49bc9e7102022-12-21T23:36:05ZengIEEEIEEE Access2169-35362019-01-01716639016639710.1109/ACCESS.2019.29539578903259Multi-Level Metric Learning Network for Fine-Grained ClassificationJiabao Wang0https://orcid.org/0000-0002-3706-9912Yang Li1https://orcid.org/0000-0003-1682-0284Zhuang Miao2https://orcid.org/0000-0003-2289-4589Xun Zhao3https://orcid.org/0000-0002-1767-6520Zhang Rui4https://orcid.org/0000-0002-3214-5330Command and Control Engineering College, Army Engineering University of PLA, Nanjing, ChinaCommand and Control Engineering College, Army Engineering University of PLA, Nanjing, ChinaCommand and Control Engineering College, Army Engineering University of PLA, Nanjing, ChinaCommand and Control Engineering College, Army Engineering University of PLA, Nanjing, ChinaCommand and Control Engineering College, Army Engineering University of PLA, Nanjing, ChinaThe application of fine-grained image classification can be problematic due to subtle differences between classes. The existing global feature-based methods have worse accuracies than regional feature-based methods, because regional feature-based methods focus on the determination of differentiated features within local regions. To learn more discriminative global features, in this paper, we proposed the use of L2 normalization to tackle a neglected conflict between the widely used metric loss (triplet loss) and classification loss (softmax loss) in global feature-based methods. Furthermore, a multi-level metric learning network (MMLN) is proposed for fine-grained image classification based on global features. In the MMLN, multi-level metric learning objectives and classification objectives are present at multiple high-level layers. The multi-level metric learning objectives work together to supervise the network in order to learn highly discriminative features. In addition, a new probability aggregation strategy (PAS) is proposed to produce a fused prediction by combining the multi-level predictive probabilities. Experiments were conducted on three standard fine-grained classification datasets (CUB-200-2011, Stanford Cars, and FGVC-Aircraft). Results demonstrated that our MMLN achieved accuracies of 88.0%, 94.6% and 92.4% respectively and outperformed state-of-the-art methods, substantially improving fine-grained classification tasks. Besides, gradient-weighted class activation mapping (Grad-CAM) shows that the MMLN is able to pay more attention to the discriminative local regions due to the application of multi-level metric learning.https://ieeexplore.ieee.org/document/8903259/Fine-grained recognitionmetric learningmulti-level objectivesclassification
spellingShingle Jiabao Wang
Yang Li
Zhuang Miao
Xun Zhao
Zhang Rui
Multi-Level Metric Learning Network for Fine-Grained Classification
IEEE Access
Fine-grained recognition
metric learning
multi-level objectives
classification
title Multi-Level Metric Learning Network for Fine-Grained Classification
title_full Multi-Level Metric Learning Network for Fine-Grained Classification
title_fullStr Multi-Level Metric Learning Network for Fine-Grained Classification
title_full_unstemmed Multi-Level Metric Learning Network for Fine-Grained Classification
title_short Multi-Level Metric Learning Network for Fine-Grained Classification
title_sort multi level metric learning network for fine grained classification
topic Fine-grained recognition
metric learning
multi-level objectives
classification
url https://ieeexplore.ieee.org/document/8903259/
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AT yangli multilevelmetriclearningnetworkforfinegrainedclassification
AT zhuangmiao multilevelmetriclearningnetworkforfinegrainedclassification
AT xunzhao multilevelmetriclearningnetworkforfinegrainedclassification
AT zhangrui multilevelmetriclearningnetworkforfinegrainedclassification