Jones, Cerys;
(2020)
An Optimised Method for Multispectral Imaging of Documentary Material.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Multispectral imaging (MSI) is often applied in the cultural heritage sector for recovering invisible features in historical documents. However, the method varies depending on the user and is typically operated by an imaging scientist. This research aimed to characterise and optimise the process of MSI so that heritage institutions could undertake their own MSI efficiently and effectively. A programme of Action Research was undertaken producing a general workflow for MSI, and recommendations for best practice and documentation. The workflow revealed areas requiring research including image registration and flat field correction. Three automatic registration techniques were compared to determine whether they could successfully correct misalignments. The mutual information method was robust and accurately aligned the images, however was computationally expensive. The phase correlation method was also successful at aligning images of the same object but failed for different objects sharing a template. The traditional method of flat field correction is most accurate for correcting the non-uniform illumination in the images, but requires capturing an additional sequence of images whenever the setup changes. Scene-based flattening methods were developed and compared for when flat field images cannot be captured. MSI is time-consuming, especially for large heritage collections. Therefore, a novel algorithm was developed to increase throughput by identifying the optimal combinations of wavelengths and filters to be captured based on principal component analysis, reducing the acquisition time in this research between 65% and 90%. This research contributes to the heritage science sector by characterising the workflow of MSI, providing recommendations for best practice and documentation, identifying registration techniques that should be used for correcting misalignment errors, developing scene-based flattening techniques for when flat field images cannot be captured, and a novel algorithm for increasing throughput in heritage institutions.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | An Optimised Method for Multispectral Imaging of Documentary Material |
| Event: | UCL (University College London) |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2020. Original content in this thesis is licensed under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) Licence (https://creativecommons.org/licenses/by/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment > Bartlett School Env, Energy and Resources |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10106532 |
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