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GPify : leveraging the combined strength of normalizing flow and softmax for an out-of-distribution aware confidence score

Kristoffersson Lind, Simon LU ; Triebel, Rudolph and Krueger, Volker LU orcid (2026) In International Journal of Computer Vision 134.
Abstract
In order for any learning-based model to be considered reliable, it needs a well-behaved uncertainty or confidence estimate. Most modern neural networks do produce a confidence estimate in the form of their softmax output probability. However, the softmax probability is invalid for out-of-distribution data. Gaussian processes are known to produce a well-behaved confidence estimate that is aware of out-of-distribution samples. Inspired by Gaussian processes, we propose GPify, which combines the softmax probability with a Normalizing Flow in order to add out-of-distribution awareness to the confidence estimate from a neural network. The resulting confidence from GPify is an uncertainty measure that is interpretable and intuitive, while also... (More)
In order for any learning-based model to be considered reliable, it needs a well-behaved uncertainty or confidence estimate. Most modern neural networks do produce a confidence estimate in the form of their softmax output probability. However, the softmax probability is invalid for out-of-distribution data. Gaussian processes are known to produce a well-behaved confidence estimate that is aware of out-of-distribution samples. Inspired by Gaussian processes, we propose GPify, which combines the softmax probability with a Normalizing Flow in order to add out-of-distribution awareness to the confidence estimate from a neural network. The resulting confidence from GPify is an uncertainty measure that is interpretable and intuitive, while also being probabilistically sound. We evaluate GPify in a selective classification framework, and conclude that it achieves comparable performance to state-of-the-art methods. In addition, we show that GPify has capabilities for detecting adversarial examples, which is a direct improvement over softmax confidence. (Less)
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publishing date
type
Contribution to journal
publication status
published
subject
in
International Journal of Computer Vision
volume
134
article number
185
pages
12 pages
publisher
Springer
external identifiers
  • scopus:105033709285
ISSN
1573-1405
language
English
LU publication?
yes
id
a4e89db4-058c-4db4-acc4-1e538b98be19
alternative location
https://link.springer.com/article/10.1007/s11263-026-02794-3
date added to LUP
2026-04-10 14:08:14
date last changed
2026-05-12 16:36:26
@article{a4e89db4-058c-4db4-acc4-1e538b98be19,
  abstract     = {{In order for any learning-based model to be considered reliable, it needs a well-behaved uncertainty or confidence estimate. Most modern neural networks do produce a confidence estimate in the form of their softmax output probability. However, the softmax probability is invalid for out-of-distribution data. Gaussian processes are known to produce a well-behaved confidence estimate that is aware of out-of-distribution samples. Inspired by Gaussian processes, we propose GPify, which combines the softmax probability with a Normalizing Flow in order to add out-of-distribution awareness to the confidence estimate from a neural network. The resulting confidence from GPify is an uncertainty measure that is interpretable and intuitive, while also being probabilistically sound. We evaluate GPify in a selective classification framework, and conclude that it achieves comparable performance to state-of-the-art methods. In addition, we show that GPify has capabilities for detecting adversarial examples, which is a direct improvement over softmax confidence.}},
  author       = {{Kristoffersson Lind, Simon and Triebel, Rudolph and Krueger, Volker}},
  issn         = {{1573-1405}},
  language     = {{eng}},
  publisher    = {{Springer}},
  series       = {{International Journal of Computer Vision}},
  title        = {{GPify : leveraging the combined strength of normalizing flow and softmax for an out-of-distribution aware confidence score}},
  url          = {{https://link.springer.com/article/10.1007/s11263-026-02794-3}},
  volume       = {{134}},
  year         = {{2026}},
}