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Extracting Chain Lines and Laid Lines from Digital Images of Medieval Paper using Spectral Total Variation Decomposition

Published version
Peer-reviewed

Repository DOI


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Authors

Großmann, Tamara 
Schönlieb, Carola-Bibiane 
Da Rold, Orietta 

Abstract

Medieval paper, a handmade product, is made with a mould which leaves an indelible imprint on the sheet of paper. This imprint includes chain lines, laid lines and watermarks which are often visible on the sheet. Extracting these features allows the identification of the paper stock and gives information about the chronology, localisation and movement of manuscripts and people. Most computational work for feature extraction of paper analysis has so far focused on radiography or transmitted light images. While these imaging methods provide clear visualisation of the features of interest, they are expensive and time consuming in their acquisition and not feasible for smaller institutions. However, reflected light images of medieval paper manuscripts are abundant and possibly cheaper in their acquisition. In this paper, we propose algorithms to detect and extract the laid and chain lines from reflected light images. We tackle the main drawback of reflected light images, that is, the low contrast attenuation of chain and laid lines and intensity jumps due to noise and degradation, by employing the spectral total variation decomposition and develop methods for subsequent chain and laid line extraction. Our results clearly demonstrate the feasibility of using reflected light images in paper analysis. This work enables feature extraction for paper manuscripts that have otherwise not been analysed due to a lack of appropriate images. We also open the door for paper stock identification at scale.

Description

Funder: Cantab Capital Institute for the Mathematics of Information


Funder: Alan Turing Institute; doi: http://dx.doi.org/10.13039/100012338

Keywords

Chain lines, Fourier, Laid lines, Mathematical image analysis, Medieval paper, Radon, Spectral total variation decomposition

Journal Title

Heritage Science

Conference Name

Journal ISSN

2050-7445
2050-7445

Volume Title

11

Publisher

SpringerOpen
Sponsorship
EPSRC (2089694)
Engineering and Physical Sciences Research Council (EP/N014588/1)
European Commission Horizon 2020 (H2020) Marie Sk?odowska-Curie actions (777826)
Engineering and Physical Sciences Research Council (EP/S515334/1)
EPSRC (EP/S026045/1)
EPSRC (EP/T017961/1)
EPSRC (EP/T003553/1)
Wellcome Trust (215733/Z/19/Z)
EPSRC (EP/V029428/1)
Wellcome Trust (221633/Z/20/Z)