What question did this study set out to answer?

This study aims to assess the colorimetric accuracy of hyperspectral imaging compared to traditional methods used for historical manuscript analysis.

May 28, 2026Open Access

Hyperspectral Imaging for the Colorimetric Characterization of Purple Manuscripts: Accuracy, Biases, and Diagnostic Potential

Key Points

This study aims to assess the colorimetric accuracy of hyperspectral imaging compared to traditional methods used for historical manuscript analysis.
Evaluated hyperspectral imaging system (Specim IQ) against a reference spectrocolorimeter (Konica-Minolta CM-700d).
Conducted laboratory measurements on certified standards and in situ analyses of purple-dyed manuscripts.
Used colorimetric coordinates (CIELAB) and color differences (ΔE00) to measure accuracy, precision, and biases.
Under controlled settings, HSI showed good accuracy in color measurement, with ΔE00 indicating slight systematic biases.
In situ accuracy was lower (average ΔE00 ≈ 4.3) due to material heterogeneity and acquisition constraints.
HSI effectively preserved relative chromatic relationships, enabling the analysis of dye distribution and degradation patterns.

Abstract

Color measurement and monitoring of chromatic changes over time play a key role in the study and conservation of historical materials. In this context, hyper-spectral imaging (HSI) offers spatially resolved spectral information that can be converted into colorimetric data, although its quantitative reliability under in situ conditions remains challenging. This study evaluates the colorimetric performance of a HSI system (Specim IQ) through comparison with a reference spectrocolorimeter (Konica-Minolta CM-700d), combining laboratory measurements on certified standards and in situ analyses on purple-dyed manuscripts. Colorimetric coordinates (CIELAB) and color differences (ΔE00) were used to assess accuracy, precision, and systematic deviations. Under controlled conditions, HSI showed good agreement with reference measurements, although systematic biases were observed. In situ applications revealed reduced accuracy (average ΔE00 ≈ 4.3) due to material heterogeneity and acquisition constraints. Despite these limitations, HSI preserved consistent relative chromatic relationships, enabling meaningful comparative analysis. Spatially resolved mapping of colorimetric parameters proved effective for visualizing chromatic variability, dye distribution, and degradation patterns. These results demonstrate that, while not fully reliable for absolute colorimetric assessment in situ, HSI represents a powerful tool for non-invasive, spatially resolved color analysis of complex historical materials.

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