Preserving Privacy Without Compromising Accuracy: Machine Unlearning for Handwritten Text Recognition

Fuente: arXiv
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Main Authors: Kang, Lei, Fu, Xuanshuo, Gomez, Lluis, Fornés, Alicia, Valveny, Ernest, Karatzas, Dimosthenis
Format: Preprint
Published: 2025
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author Kang, Lei
Fu, Xuanshuo
Gomez, Lluis
Fornés, Alicia
Valveny, Ernest
Karatzas, Dimosthenis
author_facet Kang, Lei
Fu, Xuanshuo
Gomez, Lluis
Fornés, Alicia
Valveny, Ernest
Karatzas, Dimosthenis
contents Handwritten Text Recognition (HTR) is crucial for document digitization, but handwritten data can contain user-identifiable features, like unique writing styles, posing privacy risks. Regulations such as the ``right to be forgotten'' require models to remove these sensitive traces without full retraining. We introduce a practical encoder-only transformer baseline as a robust reference for future HTR research. Building on this, we propose a two-stage unlearning framework for multihead transformer HTR models. Our method combines neural pruning with machine unlearning applied to a writer classification head, ensuring sensitive information is removed while preserving the recognition head. We also present Writer-ID Confusion (WIC), a method that forces the forget set to follow a uniform distribution over writer identities, unlearning user-specific cues while maintaining text recognition performance. We compare WIC to Random Labeling, Fisher Forgetting, Amnesiac Unlearning, and DELETE within our prune-unlearn pipeline and consistently achieve better privacy and accuracy trade-offs. This is the first systematic study of machine unlearning for HTR. Using metrics such as Accuracy, Character Error Rate (CER), Word Error Rate (WER), and Membership Inference Attacks (MIA) on the IAM and CVL datasets, we demonstrate that our method achieves state-of-the-art or superior performance for effective unlearning. These experiments show that our approach effectively safeguards privacy without compromising accuracy, opening new directions for document analysis research. Our code is publicly available at https://github.com/leitro/WIC-WriterIDConfusion-MachineUnlearning.
format Preprint
id arxiv_https___arxiv_org_abs_2504_08616
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Preserving Privacy Without Compromising Accuracy: Machine Unlearning for Handwritten Text Recognition
Kang, Lei
Fu, Xuanshuo
Gomez, Lluis
Fornés, Alicia
Valveny, Ernest
Karatzas, Dimosthenis
Computer Vision and Pattern Recognition
Handwritten Text Recognition (HTR) is crucial for document digitization, but handwritten data can contain user-identifiable features, like unique writing styles, posing privacy risks. Regulations such as the ``right to be forgotten'' require models to remove these sensitive traces without full retraining. We introduce a practical encoder-only transformer baseline as a robust reference for future HTR research. Building on this, we propose a two-stage unlearning framework for multihead transformer HTR models. Our method combines neural pruning with machine unlearning applied to a writer classification head, ensuring sensitive information is removed while preserving the recognition head. We also present Writer-ID Confusion (WIC), a method that forces the forget set to follow a uniform distribution over writer identities, unlearning user-specific cues while maintaining text recognition performance. We compare WIC to Random Labeling, Fisher Forgetting, Amnesiac Unlearning, and DELETE within our prune-unlearn pipeline and consistently achieve better privacy and accuracy trade-offs. This is the first systematic study of machine unlearning for HTR. Using metrics such as Accuracy, Character Error Rate (CER), Word Error Rate (WER), and Membership Inference Attacks (MIA) on the IAM and CVL datasets, we demonstrate that our method achieves state-of-the-art or superior performance for effective unlearning. These experiments show that our approach effectively safeguards privacy without compromising accuracy, opening new directions for document analysis research. Our code is publicly available at https://github.com/leitro/WIC-WriterIDConfusion-MachineUnlearning.
title Preserving Privacy Without Compromising Accuracy: Machine Unlearning for Handwritten Text Recognition
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2504.08616