Open Access spectral data for documentary heritage digitisation

Open Access spectral data for documentary heritage digitisation
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img. Standard set-up for high quality, color-profiled photography at the KU leuven Libraries Digital Lab.

A post by Hendrik Hameeuw & Bruno Vandermeulen, recently published on KU Leuven’s blog “Enriching Heritage“, presents the publication of an open access spectral dataset which, beside other areas of application, provides insights and opportunities for better fine-tuned digitisation results for documentary heritage.

The Imaging Lab of KU Leuven Libraries has a strong focus on digitisation and imaging of documentary heritage. A crucial step in the digitisation process is the image creation; the transition of the physical object into a bitmap or array of pixels. During this process the colors of the object to be photographed, have to be translated into a particular colorimetric value at pixel base. The better that translation is fine-tuned, the more accurate the final result will be and the more the viewer can be assured the digital presentation matches the original object as it would appears in similar lighting conditions (=reliable data). This also means to define the discrepancy between the colors on the reference color target and the colors of the documentary heritage that is digitized, trying to understand whether the existence of such discrepancy – the gap – is a pure theoretical problem or a real life issue.

At the Imaging Lab of KU Leuven Libraries we decided to make that effort. In collaboration with colleagues of Special Collections we defined which original historical materials are representative for KU Leuven’s library heritage and archive collections and started measuring their spectral responses with a standard reflective spectrometer (Eye-One (i1) Pro Photo). As such, an insight has been obtained by providing the spectral responses and corresponding colors with their attested tints, tones, shades and hues typical for documentary heritage.

A lot more reflections derived from this analysis.

This video below visualises the ‘KU Leuven Libraries Open Access Spectral Data of historical paper, parchment/vellum, leather, inks and pigments’,and it also includes a comparison of that dataset with the SG ColorChecker and the FADGI ISO19264 device level targets. The videopresentation was made by Don Williams (Image Science Associates), edited by Peter Burns.

The entire KU Leuven Libraries spectral data has been published online as open data. Together with the needed documentation this give the opportunity to use this data for any future work for which spectral characterisation of documentary heritage materials is wanted. The dataset is published on zenodo.org as Hameeuw Hendrik, Vandermeulen Bruno, Van Cutsem Frédéric, Smets An & Snijders Tjamke (2021): KU Leuven Libraries Open access Spectral data of historical paper, parchment/vellum, leather, inks and pigments (Version 1.0) [Data set]. http://doi.org/10.5281/zenodo.3965419.

Feel free to work with the dataset. When you do, do not hesitate to reach out to us if you have any questions. If you have feedback and/or are interested to collaborate on the topic: digitalisering@kuleuven.be.

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