Simulating analogue film damage to analyse and improve artefact restoration on high-resolution scans

Ivanova, D., Williamson, J. and Henderson, P. (2023) Simulating analogue film damage to analyse and improve artefact restoration on high-resolution scans. Computer Graphics Forum, 42(2), pp. 133-148. (doi: 10.1111/cgf.14749)

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Abstract

Digital scans of analogue photographic film typically contain artefacts such as dust and scratches. Automated removal of these is an important part of preservation and dissemination of photographs of historical and cultural importance. While state-of-the-art deep learning models have shown impressive results in general image inpainting and denoising, film artefact removal is an understudied problem. It has particularly challenging requirements, due to the complex nature of analogue damage, the high resolution of film scans, and potential ambiguities in the restoration. There are no publicly available high-quality datasets of real-world analogue film damage for training and evaluation, making quantitative studies impossible. We address the lack of ground-truth data for evaluation by collecting a dataset of 4K damaged analogue film scans paired with manually-restored versions produced by a human expert, allowing quantitative evaluation of restoration performance. We have made the dataset available at https://doi.org/10.6084/m9.figshare.21803304. We construct a larger synthetic dataset of damaged images with paired clean versions using a statistical model of artefact shape and occurrence learnt from real, heavily-damaged images. We carefully validate the realism of the simulated damage via a human perceptual study, showing that even expert users find our synthetic damage indistinguishable from real. In addition, we demonstrate that training with our synthetically damaged dataset leads to improved artefact segmentation performance when compared to previously proposed synthetic analogue damage overlays. The synthetically damaged dataset can be found at https://doi.org/10.6084/m9.figshare.21815844, and the annotated authentic artefacts along with the resulting statistical damage model at https://github.com/daniela997/FilmDamageSimulator. Finally, we use these datasets to train and analyse the performance of eight state-of-the-art image restoration methods on high-resolution scans. We compare both methods which directly perform the restoration task on scans with artefacts, and methods which require a damage mask to be provided for the inpainting of artefacts. We modify the methods to process the inputs in a patch-wise fashion to operate on original high resolution film scans.

Item Type:Articles
Additional Information:Conference paper first presented at the 44th Annual Conference of the European Association for Computer Graphics (Eurographics 2023), Saarbrücken, Germany, 08-12 May 2023.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Ivanova, Ms Daniela and Henderson, Dr Paul and Williamson, Dr John
Authors: Ivanova, D., Williamson, J., and Henderson, P.
College/School:College of Science and Engineering > School of Computing Science
Research Centre:College of Science and Engineering > School of Computing Science > IDA Section > GPU Cluster
Journal Name:Computer Graphics Forum
Publisher:Wiley
ISSN:0167-7055
ISSN (Online):1467-8659
Published Online:23 May 2023
Copyright Holders:Copyright © 2023 The Authors
First Published:First published in Computer Graphics Forum 42(2): 133-148
Publisher Policy:Reproduced under a Creative Commons License
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
305200DTP 2018-19 University of GlasgowMary Beth KneafseyEngineering and Physical Sciences Research Council (EPSRC)EP/R513222/1MVLS - Graduate School