Understanding multispectral imaging of cultural heritage: Determining best practice in MSI analysis of historical artefacts

Abstract

Although multispectral imaging (MSI) of cultural heritage, such as manuscripts, documents and artwork, is becoming more popular, a variety of approaches are taken and methods are often inconsistently documented. Furthermore, no overview of the process of MSI capture and analysis with current technology has previously been published. This research was undertaken to determine current best practice in the deployment of MSI, highlighting areas that need further research, whilst providing recommendations regarding approach and documentation. An Action Research methodology was used to characterise the current pipeline, including: literature review; unstructured interviews and discussion of results with practitioners; and reflective practice whilst undertaking MSI analysis. The pipeline and recommendations from this research will improve project management by increasing clarity of published outcomes, the reusability of data, and encouraging a more open discussion of process and application within the MSI community. The importance of thorough documentation is emphasised, which will encourage sharing of best practice and results, improving community deployment of the technique. The findings encourage efficient use and reporting of MSI, aiding access to historical analysis. We hope this research will be useful to digitisation professionals, curators and conservators, allowing them to compare and contrast current practices. Highlights:• A range of approaches are undertaken for multispectral imaging of heritage.• An Action Research methodology was used to characterise the current pipeline.• A set of recommendations for best practice and documentation are provided.

Pitfalls and Possibilities of Patinated Bronze: The Analysis of Pre-Roman Italian Armour Using pXRF

“…This is an area where changes in conservation practice could help with future work, as an analysis of the soil removed from excavated bronzes during the initial cleaning of an artefact and from various sections of the excavated bronze would be useful in understanding the patination process and how it may have impacted the readings. There is also some opacity about conservation practices, particularly in earlier periods of modern cultural heritage management, due to the different objectives of academic and heritage institutions [61]. Since the 1980s, conservation often includes being cleaned mechanically and being treated for bronze disease using benzotriazole, before any fragments are jointed together, gaps filled with plasticine vel sim and modelling paste, and then being painted [62].…”

Multiband Photogrammetry and Hybrid Image Analysis for the Investigation of a Wall Painting by Paolo de San Leocadio and Francesco Pagano in the Cathedral of Valencia

“…Already the definitions of the two most known methods, multispectral imaging (MSI) and hyperspectral imaging (HSI), vary [ 1 ]. The main differentiation is given by the number of spectral bands captured, where MSI applies between four and ten bands, while in HSI up to several hundred bands are used [ 2 , 3 ]. In addition, the way the single image bands are captured is a common way to distinguish between HSI and MSI.…”

“…In HSI, the bandwidth is very narrow, around 10 nm or less, whereas in MSI it is around 10 to 40 nm [ 2 , 8 , 9 ]. However, the term MSI is also commonly used for spectral imaging with longer bandwidths, especially for the observation of CH [ 3 , 10 ]. For a better differentiation of spectral imaging between defined (narrow) band filters of up to 40 nm (MSI) and the use of broadband filters, several new terms have been introduced during the last few years.…”

Integration of multispectral imaging, XRF mapping and Raman analysis for noninvasive study of illustrated manuscripts: the case study of fifteenth century “Humay meets the Princess Humayun” Persian masterpiece from Louvre Museum

“…In the investigation of painted surfaces, multispectral imaging data (or hyperspectral) and processing methods [1][2][3][4] provide new information on painting materials and techniques used for production [5][6][7] as well as support to authentication issues [8] and evaluation of the general state of conservation of an artwork [9,10]. Cutting-edge MSI techniques coupled with a well-established choice of image processing procedures [11] can provide valuable set of information in situ, with reduced time of acquisition and data analysis. This leads to a diagnostic frame of the investigated artwork which can serve as a basis for subsequent analysis strategy in material characterization and monitoring [12].…”