On the Shift Invariance of Max Pooling Feature Maps in Convolutional Neural Networks

Fuente: arXiv
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Autori principali: Leterme, Hubert, Polisano, Kévin, Perrier, Valérie, Alahari, Karteek
Natura: Preprint
Pubblicazione: 2022
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author Leterme, Hubert
Polisano, Kévin
Perrier, Valérie
Alahari, Karteek
author_facet Leterme, Hubert
Polisano, Kévin
Perrier, Valérie
Alahari, Karteek
contents This paper focuses on improving the mathematical interpretability of convolutional neural networks (CNNs) in the context of image classification. Specifically, we tackle the instability issue arising in their first layer, which tends to learn parameters that closely resemble oriented band-pass filters when trained on datasets like ImageNet. Subsampled convolutions with such Gabor-like filters are prone to aliasing, causing sensitivity to small input shifts. In this context, we establish conditions under which the max pooling operator approximates a complex modulus, which is nearly shift invariant. We then derive a measure of shift invariance for subsampled convolutions followed by max pooling. In particular, we highlight the crucial role played by the filter's frequency and orientation in achieving stability. We experimentally validate our theory by considering a deterministic feature extractor based on the dual-tree complex wavelet packet transform, a particular case of discrete Gabor-like decomposition.
format Preprint
id arxiv_https___arxiv_org_abs_2209_11740
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle On the Shift Invariance of Max Pooling Feature Maps in Convolutional Neural Networks
Leterme, Hubert
Polisano, Kévin
Perrier, Valérie
Alahari, Karteek
Computer Vision and Pattern Recognition
Artificial Intelligence
Signal Processing
Machine Learning
This paper focuses on improving the mathematical interpretability of convolutional neural networks (CNNs) in the context of image classification. Specifically, we tackle the instability issue arising in their first layer, which tends to learn parameters that closely resemble oriented band-pass filters when trained on datasets like ImageNet. Subsampled convolutions with such Gabor-like filters are prone to aliasing, causing sensitivity to small input shifts. In this context, we establish conditions under which the max pooling operator approximates a complex modulus, which is nearly shift invariant. We then derive a measure of shift invariance for subsampled convolutions followed by max pooling. In particular, we highlight the crucial role played by the filter's frequency and orientation in achieving stability. We experimentally validate our theory by considering a deterministic feature extractor based on the dual-tree complex wavelet packet transform, a particular case of discrete Gabor-like decomposition.
title On the Shift Invariance of Max Pooling Feature Maps in Convolutional Neural Networks
topic Computer Vision and Pattern Recognition
Artificial Intelligence
Signal Processing
Machine Learning
url https://arxiv.org/abs/2209.11740