Multispectral Imaging (MSI)

Multispectral Imaging (MSI) in cultural heritage is commonly used for recovering lost, damaged or otherwise illegible writing (see research question 4) without destroying, damaging or altering the original artefact. The process of MSI consists of collecting spectral information through imaging and later revealing the lost writing through image processing. During imaging, the object is photographed under 19 distinct wavelengths of light that range from the ultraviolet (UV) to the infrared (IR) regions (365–1050 nm). These wavelengths are employed in four modalities — reflectance, fluorescence, raking, and transmissive — and result in up to 50 images per capture sequence. These registered, high-resolution, greyscale images are combined into a three-dimensional “image cube” to which mathematical processes are then performed in order to enhance or reduce the contrast of specific pixels, usually with the goal of making the desired text more visible (Digital Images). A final set of “processed” images with the lost writing made legible is produced without damaging the object. See MSI data.