Launch pixel+ viewer: New dimensions take a deeper look at heritage

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Together with the Art & History Museum and the Royal Library of Belgium (KBR), KU Leuven is launching an online open access application to view heritage objects dynamically and interactively online. This pixel+ viewer allows you to view centuries-old objects in a different light and reveal hidden details.  

Japanese print on paper (© KU Leuven Libraries collections) in the pixel+ viewer

As a result of the Corona crisis, museums and other heritage institutions today have little or no physical access, both in Belgium and abroad. It puts the consultation of objects and the study of our past under strong pressure. In part, we can fall back on digitised objects, notes and old publications, but these only represent part of the information, which means that important details can be overlooked. Fortunately, the sector, in collaboration with engineers, has devised solutions to remedy this.

In the heritage sector, the digitisation of objects has long been the focus of attention and experimentation. For the public, this usually results in an online photo that can be zoomed in or on which the contrast can be adjusted. These are purely colour images, standard digital photographs conceal no extra information. However, different types of image scanners register a lot more characteristics of a surface than just the colour. Being able to visualize this information in a handy online tool therefore offers new possibilities for anyone working with heritage objects. Think, for example, of the KBR drawings by Pieter Bruegel the Elder that were recently examined by KU Leuven. The researchers were able to study the paper down to the fibre using their Portable Light Dome (PLD) scanner. They also got a much better view of the extensive range of techniques used by the old master.

Detail on original Pieter Bruegel the Old drawing from 1557 (KBR: II132816, Luxuria), without colour the imprinted stylus traces of the engraver become visible (© Fingerprint, KBR and KU Leuven).

Software is the key

Over the past 15 years, KU Leuven researchers, together with various partners from the heritage sector, have developed digital techniques that can visualise objects to an unprecedented level of detail: the PLD scanner. “With this method, they illuminate an object from a large number of angles and take photos of it, the so-called ‘single-camera, multi-light recording’, says Hendrik Hameeuw, co-coordinator of the project at KU Leuven. “The way in which this recording is subsequently processed determines which characteristics of the surface, such as relief or texture, the software can show and thus how the user experiences the object”.

New universal file format

 “To be entirely complete, we actually have to look at the file types of these interactive datasets,” says Hameeuw. Most heritage institutions calculate and store these types of images of their heritage with a specific image format, usually RTI/HSH. The software developed in Leuven works with PLD files (ZUN, CUN) that have extra functionalities compared to those RTI/HSH files. Pixel+ now makes this way of calculation available to the whole world, not only by offering it online, but also by introducing a new kind of container file for it: glTF. “Compare it with an ordinary photo on your computer. It will probably be a JPEG or GIF file. But if you want to work with it in Photoshop, the program will turn the same image into a PSD file”. These glTFs are compatible with both the Leuven PLD and the RTI/HSH files. “With this we offer a new universal standard for this kind of images and we also open them immediately via the online pixel+ viewer, a kind of free photoshop for ‘single-camera, multi-light recording’ images”. This allows both RTI/HSH and PLD files to be studied and compared within the same program for the first time.µ

A new world

Pixel+ extracts a lot of extra information from the available data. The objects, such as old coins, miniatures or paintings, suddenly acquire extra dimensions after hundreds of years, which can be used for research on these objects to gain new insights. Especially in the field of 3D (geometry) and the correct understanding of the reflections of light on an object, the Leuven software is taking major steps forward.

“The technology is interesting for many objects, from clay tablets over coins to paintings or medieval manuscripts,” explains Hameeuw. “The software allows, among other things, the objects to be viewed virtually with different incidence of light, the relief to be mapped at pixel level or a 3D visualisation to be generated”. Frédéric Lemmers of the KBR Digitisation Department joins in: “By even combining it with multi-spectral imaging, researchers recently discovered that the heads of some figures in KBR’s 13th-century Rijmbijbel were painted over at a later date.” At the Art & History Museum, the technology was used to make heavily weathered texts on almost 4,000-year-old Egyptian figurines readable again.

Institutions from all over the world, from the Metropolitan Museum of Art in New York (USA) to the Regionaal Archeologisch Museum a/d Schelde in Avelgem (Belgium), will be able to upload, consult and study their own datasets or files in pixel+. The software converts the information according to various new standards and allows users to access the virtual heritage objects interactively. “This development really is a milestone for the heritage sector”, emphasises Chris Vastenhoud, promoter of the project from the Art & History Museum. “A whole new world will open up for heritage institutions worldwide. They will be able to document and share a lot of additional information in order to communicate about the objects in their collections”.

Pixel+ is available to everyone at http://www.heritage-visualisation.org with examples of objects from the collections of the Art & History Museum, KBR and KU Leuven.


The online pixel+ viewer with an example of a cuneiform tablet from the collection of the Museum Art & History, Brussels. (© Art & History Museum and KU Leuven).

The project is a collaboration between Art & History Museum, KU Leuven Department of Electrical Engineering, KU Leuven Illuminare, KU Leuven Libraries Digitisation and KBR; and was funded by the Federal Science Policy Office (BELSPO) through the BRAIN-be programme (Pioneer projects).

Contact list of all partners involved:

At the beginning of April 2020, the pixel+ project staff already presented their results during the online (as a result of Corona) SPIE conference. As a result, the paper below was published: 

Vincent Vanweddingen, Hendrik Hameeuw, Bruno Vandermeulen, Chris Vastenhoud, Lieve Watteeuw, Frédéric Lemmers, Athena Van der Perre, Paul Konijn, Luc Van Gool, Marc Proesmans 2020: Pixel+: integrating and standardizing of various interactive pixel-based imagery, in: Peter Schelkens, Tomasz Kozacki (eds.) Optics, Photonics and Digital Technologies for Imaging Applications VI, Proc. of SPIE Vol. 11353, 113530G. (DOI: 10.1117/12.2555685)

read paper – see presentation

Additional examples can be viewed and created at http://www.heritage-visualisation.org/examples.html

FINGERPRINT project in KU Leuven Campuskrant

Cartoon by Joris Snaert © on the use of the Portable Light Dome when digitizing a Bruegel drawing (page 2 of Campuskrant 31/1) 

An interview in the KU Leuven university journal Campuskrant with prof. Lieve Watteeuw the KU Leuven, contributions to the FINGERPRINT project have been highlighted in length. The Campus article focuses on the work with the original drawings by Pieter Bruegel the Elder and how the imaging effort by the FINGERPRINT-team have made the difference to better understand the virtuosity of Breugel the artist.  These results will also be presented on the KBR exhibition: The World of Bruegel in Black and White.

The Imaging Lab was responsible for the digitisation of all drawings and prints and also carried out the advanced imaging enabling in-depth visualisations.

PDF of the complete campuskrant edition

More info on the Fingerprint Blog

Introducing EXPO

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KU Leuven Libraries is happy to present a new online platform for accessing its fragile heritage collections online: EXPO.

EXPO offers virtual exhibitions and a gallery of individual collection items, and informs about digitization and imaging projects at the library.

The virtual exhibitions connect collection items with other works and may or may not be a continuation of actual library exhibitions. Exceptional works from the KU Leuven Libraries’ collections are highlighted in the gallery, which gathers both recognized masterpieces and other fascinating works with a unique story. The project pages introduce the website visitor to ongoing and past activities in the field of digitization. Both initiatives aiming at the digital disclosure of the library collections as well as projects in the context of research and technical imaging are presented.

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EXPO is the result of a close collaboration between various departments. Exhibition curators, collection keepers, and other heritage collaborators and partners create the exhibitions and fill the gallery with collection highlights. LIBIS carried out the technical implementation of the site as part of the Heron (Heritage Online) service. The site is based on the open source web publishing platform Omeka. For the site’s development, LIBIS created a direct connection between Omeka, the library management system Alma and the preservation system Teneo/Rosetta, allowing curators to work within a single, integrated environment. The coordination of EXPO is taken on by KU Leuven Libraries Digitisation & Document Delivery. This department manages digitisation projects, executes digitisation in its Imaging Lab and supports research projects with bespoke digitisation techniques and the specific expertise required for scientific imaging.

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Introducing ArtGarden

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The Imaging Lab is partner in the ArtGarden research project. The project aims to test and develop an efficient (“best practices”) matrix (tool – protocol) for monitoring, imaging and documenting (art-technical), fragile historic mixed media objects. This is used to facilitate decision making during conservation and preservation practice.

The Imaging Lab is involved to investigate the historical materials and techniques through scientific imaging tools such as multi-spectral imaging or the Microdome (developed within the RICH project)

The focus of the project is the guiding and evaluation of conservation treatment and the transportation, display in a museum environment and long-term storage of complex degraded historic mixed media artefacts. Up until now, guidelines have concentrated on one material characteristic. The complex nature of a large number of historic mixed-media artefacts in museum collections is more challenging and less developed. The ArtGarden project combines documentation, conservation and preservation protocols (Terminology defined by ICOM-CC, New Delhi, 2008) to create an innovative tool to support collection care, maintenance, display and valorization of complex historic collection artefacts.

Royal Institute for Cultural Heritage, KIK/IRPA
KU Leuven
University of Antwerp

A project funded by Belspo/BRAIN.

Introducing Fingerprint: an interdisciplinary research project on the graphic works of Pieter Bruegel the Elder

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Pieter Bruegel, Justitia, S II 133 707 (detail), 1559, 224 x 295 mm, KBR Print Room, Brussels, Imaging with Multi-Spectral Microdome (RICH project)

The Imaging Lab is one of the partners in FINGERPRINT: an interdisciplinary collection- and data management project, involving art history, art technical research, digital imaging, image processing, conservation science.

The aim is to monitor and evaluate the phases of the genesis of a print, from the unique preparatory drawings over proof impressions to later states and editions. This will be accomplished through advanced digital imaging, statistical processing and laboratory analyses.

The graphic works of Pieter Bruegel the Elder (ca. 1520-1569) in the collection of the Royal Library of Belgium is the test corpus for the FINGERPRINT project. The tools and methods developed to gather and treat the data will be designed to answer specific questions regarding the prints and drawings from this corpus. These questions concern both collection management, technical art history and conservation science as well as production, distribution and consumption history of the corpus of artifacts of Bruegel. Continue reading

The 8th century Codex Eyckensis digitised and made available online

Codex Eyckensis

Codex Eyckensis A

In close collaboration with Prof. Lieve Watteeuw (Illuminare – Centre for the Study of Medieval Art), the Imaging Lab meticulously digitised the Codex Eyckensis. The codex is the oldest preserved “book” produced in the Low Countries, the wider area encompassing contemporary Belgium, the Netherlands and Luxembourg. The Codex can now be accessed online through LIBIS. Continue reading