Hirokatsu KATAOKA, Ph.D.
National Institute of Advanced Industrial Science and Technology (AIST), Japan

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"Feature Evaluation of Deep Convolutional Neural Networks for Object Recognition and Detection"
Hirokatsu Kataoka, Kenji Iwata, Yutaka Satoh (AIST)

  In this paper, we evaluate convolutional neural network (CNN) features using the AlexNet architecture and very deep convolutional network (VGGNet) architecture. To date, most CNN researchers have employed the last layers before output, which were extracted from the fully connected feature layers. However, since it is unlikely that feature representation effectiveness is dependent on the problem, this study evaluates additional convolutional layers that are adjacent to fully connected layers, in addition to executing simple tuning for feature concatenation (e.g., layer 3 + layer 5 + layer 7) and transformation, using tools such as principal component analysis. In our experiments, we carried out detection and classification tasks using the Caltech 101 and Daimler Pedestrian Benchmark Datasets.

  The right figure shows VGGNet, AlexNet, and their compressed features with PCA (VGGNet(PCA) and AlexNet(PCA)). As for VGGNet, layers 5 and 6 achieved the best results (91.8%) on the Caltech 101 dataset. However, these results show significant layer 5 differences between VGGNet (91.8%) and AlexNet (78.3%). From the results, it can be seen that features obtained from fully connected layers do not always provide the highest performance rates during recognition and detection tasks, and that middle-layer features are more flexible for some tasks. We also found that fully connected layers or max-pooling layers located near fully connected layers tend to perform better in general object recognition tasks, such as the Caltech 101 dataset.


References

- Hirokatsu Kataoka,Kenji Iwata, Yutaka Satoh, "Feature Evaluation of Deep Convolutional Neural Networks for Object Recognition and Detection", arXiv preprint arXiv:1509.07627, Sep. 2015.[PDF] [SlideShare]




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