Feature hallucination in hypersphere space for few‐shot classification

Abstract Few‐shot classification (FSC) targeting at classifying unseen classes with few labelled samples is still a challenging task. Recent works show that transfer‐learning based approaches are competitive with meta‐learning ones, which usually pre‐train a convolutional neural networks (CNN)‐based...

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Main Authors: Sai Yang, Fan Liu, Zhiyu Chen
Format: Article
Language:English
Published: Wiley 2022-11-01
Series:IET Image Processing
Online Access:https://doi.org/10.1049/ipr2.12579
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author Sai Yang
Fan Liu
Zhiyu Chen
author_facet Sai Yang
Fan Liu
Zhiyu Chen
author_sort Sai Yang
collection DOAJ
description Abstract Few‐shot classification (FSC) targeting at classifying unseen classes with few labelled samples is still a challenging task. Recent works show that transfer‐learning based approaches are competitive with meta‐learning ones, which usually pre‐train a convolutional neural networks (CNN)‐based network using cross‐entropy (CE) loss and throw away the last layer to post‐process the novel classes. Hereby, they still suffer the issue of getting a more transferable extractor and lacking enough labelled novel samples. Thus, the authors propose the algorithm of feature hallucination in hypersphere space (FHHS) for FSC. On the first stage, the authors pre‐train a more transferable feature extractor using a hypersphere loss (HL), which supplies CE with supervised contrastive (SC) loss and self‐supervised loss (SSL), in which SC can map the base and novel images onto the hypersphere space densely. On the second stage, the authors generate new samples for unseen classes using their novel algorithm of synthetic novel sampling with the base (SNSB), which linearly interpolate between each novel class prototype and its K nearest neighbour base class prototypes. Comprehensive experiments on multiple popular FSC demonstrate that HL loss can enhance the performance of backbone network and the authors’ feature hallucination method is superior to the existing hallucination‐based methods.
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spelling doaj.art-27189c89dc9a4fae996fdae215ee4acc2022-12-22T02:25:59ZengWileyIET Image Processing1751-96591751-96672022-11-0116133603361610.1049/ipr2.12579Feature hallucination in hypersphere space for few‐shot classificationSai Yang0Fan Liu1Zhiyu Chen2School of Electrical Engineering Nantong University Nantong Jiangsu ChinaCollege of Computer and Information Hohai University Nanjing Jiangsu ChinaCollege of Computer and Information Hohai University Nanjing Jiangsu ChinaAbstract Few‐shot classification (FSC) targeting at classifying unseen classes with few labelled samples is still a challenging task. Recent works show that transfer‐learning based approaches are competitive with meta‐learning ones, which usually pre‐train a convolutional neural networks (CNN)‐based network using cross‐entropy (CE) loss and throw away the last layer to post‐process the novel classes. Hereby, they still suffer the issue of getting a more transferable extractor and lacking enough labelled novel samples. Thus, the authors propose the algorithm of feature hallucination in hypersphere space (FHHS) for FSC. On the first stage, the authors pre‐train a more transferable feature extractor using a hypersphere loss (HL), which supplies CE with supervised contrastive (SC) loss and self‐supervised loss (SSL), in which SC can map the base and novel images onto the hypersphere space densely. On the second stage, the authors generate new samples for unseen classes using their novel algorithm of synthetic novel sampling with the base (SNSB), which linearly interpolate between each novel class prototype and its K nearest neighbour base class prototypes. Comprehensive experiments on multiple popular FSC demonstrate that HL loss can enhance the performance of backbone network and the authors’ feature hallucination method is superior to the existing hallucination‐based methods.https://doi.org/10.1049/ipr2.12579
spellingShingle Sai Yang
Fan Liu
Zhiyu Chen
Feature hallucination in hypersphere space for few‐shot classification
IET Image Processing
title Feature hallucination in hypersphere space for few‐shot classification
title_full Feature hallucination in hypersphere space for few‐shot classification
title_fullStr Feature hallucination in hypersphere space for few‐shot classification
title_full_unstemmed Feature hallucination in hypersphere space for few‐shot classification
title_short Feature hallucination in hypersphere space for few‐shot classification
title_sort feature hallucination in hypersphere space for few shot classification
url https://doi.org/10.1049/ipr2.12579
work_keys_str_mv AT saiyang featurehallucinationinhyperspherespaceforfewshotclassification
AT fanliu featurehallucinationinhyperspherespaceforfewshotclassification
AT zhiyuchen featurehallucinationinhyperspherespaceforfewshotclassification