NAF-DPM: A Nonlinear Activation-Free Diffusion Probabilistic Model for Document Enhancement

Fuente: arXiv
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Auteurs principaux: Cicchetti, Giordano, Comminiello, Danilo
Format: Preprint
Publié: 2024
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author Cicchetti, Giordano
Comminiello, Danilo
author_facet Cicchetti, Giordano
Comminiello, Danilo
contents Real-world documents may suffer various forms of degradation, often resulting in lower accuracy in optical character recognition (OCR) systems. Therefore, a crucial preprocessing step is essential to eliminate noise while preserving text and key features of documents. In this paper, we propose NAF-DPM, a novel generative framework based on a diffusion probabilistic model (DPM) designed to restore the original quality of degraded documents. While DPMs are recognized for their high-quality generated images, they are also known for their large inference time. To mitigate this problem we provide the DPM with an efficient nonlinear activation-free (NAF) network and we employ as a sampler a fast solver of ordinary differential equations, which can converge in a few iterations. To better preserve text characters, we introduce an additional differentiable module based on convolutional recurrent neural networks, simulating the behavior of an OCR system during training. Experiments conducted on various datasets showcase the superiority of our approach, achieving state-of-the-art performance in terms of pixel-level and perceptual similarity metrics. Furthermore, the results demonstrate a notable character error reduction made by OCR systems when transcribing real-world document images enhanced by our framework. Code and pre-trained models are available at https://github.com/ispamm/NAF-DPM.
format Preprint
id arxiv_https___arxiv_org_abs_2404_05669
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle NAF-DPM: A Nonlinear Activation-Free Diffusion Probabilistic Model for Document Enhancement
Cicchetti, Giordano
Comminiello, Danilo
Computer Vision and Pattern Recognition
Real-world documents may suffer various forms of degradation, often resulting in lower accuracy in optical character recognition (OCR) systems. Therefore, a crucial preprocessing step is essential to eliminate noise while preserving text and key features of documents. In this paper, we propose NAF-DPM, a novel generative framework based on a diffusion probabilistic model (DPM) designed to restore the original quality of degraded documents. While DPMs are recognized for their high-quality generated images, they are also known for their large inference time. To mitigate this problem we provide the DPM with an efficient nonlinear activation-free (NAF) network and we employ as a sampler a fast solver of ordinary differential equations, which can converge in a few iterations. To better preserve text characters, we introduce an additional differentiable module based on convolutional recurrent neural networks, simulating the behavior of an OCR system during training. Experiments conducted on various datasets showcase the superiority of our approach, achieving state-of-the-art performance in terms of pixel-level and perceptual similarity metrics. Furthermore, the results demonstrate a notable character error reduction made by OCR systems when transcribing real-world document images enhanced by our framework. Code and pre-trained models are available at https://github.com/ispamm/NAF-DPM.
title NAF-DPM: A Nonlinear Activation-Free Diffusion Probabilistic Model for Document Enhancement
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2404.05669