Fragments under the Lens: A Case Study of Multispectral versus Hyperspectral Imaging for Manuscript Recovery

Abstract

This article seeks to clarify the varied utilities of multispectral imaging (MSI) and hyperspectral imaging (HSI) for the purposes of fragment recovery and analysis. The two technologies are discussed in detail, with the aim of explaining their functionality and required methodology to a humanities-oriented audience. For purposes of comparison, two medieval manuscript fragments—one a palimpsest, the other damaged by abrasion and staining—were imaged using both MSI and HSI systems. The data sets were then compared using several metrics and the results outlined. MSI was found to have significantly better spatial resolution (the amount of fine detail that the system is capable of capturing), while HSI had vastly better spectral resolution (the number of wavelengths discerned by the system). The MSI system also displayed a superior signal-to-noise ratio (SNR) and edge response, meaning that images were clearer and sharper. MSI images enabled the identification, transcription, and approximate dating of the palimpsested fragment, but the less visually clear HSI data set failed to fully do so. However, the superior spectral resolution of the HSI system allowed for the noninvasive and nondestructive identification of inks and pigments and enabled our team to differentiate between even those that appear to be identical to the naked eye. In this case, the red pigment used on the palimpsest was identified from the hyperspectral data but could not be from the multispectral. Our conclusion is that HSI systems can offer valuable information about material composition and history and may shed light on provenance. Neither system is universally superior; the choice of which one to employ depends upon what questions a scholar seeks to ask of the object.