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Multimodal imaging of papyrus article in Heritage Science journal

Lucy JStagg23 March 2018

The team behind the UCLDH Research Project Deep Imaging Egyptian Mummy Cases is pleased to have an article published in the Springer Heritage Science Journal 2018 6:7.

The article is ‘An assessment of multimodal imaging of subsurface text in mummy cartonnage using surrogate papyrus phantoms’ and the abstract reads as follows:

Ancient Egyptian mummies were often covered with an outer casing, panels and masks made from cartonnage: a lightweight material made from linen, plaster, and recycled papyrus held together with adhesive. Egyptologists, papyrologists, and historians aim to recover and read extant text on the papyrus contained within cartonnage layers, but some methods, such as dissolving mummy casings, are destructive. The use of an advanced range of different imaging modalities was investigated to test the feasibility of non-destructive approaches applied to multi-layered papyrus found in ancient Egyptian mummy cartonnage. Eight different techniques were compared by imaging four synthetic phantoms designed to provide robust, well-understood, yet relevant sample standards using modern papyrus and replica inks. The techniques include optical (multispectral imaging with reflection and transillumination, and optical coherence tomography), X-ray (X-ray fluorescence imaging, X-ray fluorescence spectroscopy, X-ray micro computed tomography and phase contrast X-ray) and terahertz-based approaches. Optical imaging techniques were able to detect inks on all four phantoms, but were unable to significantly penetrate papyrus. X-ray-based techniques were sensitive to iron-based inks with excellent penetration but were not able to detect carbon-based inks. However, using terahertz imaging, it was possible to detect carbon-based inks with good penetration but with less sensitivity to iron-based inks. The phantoms allowed reliable and repeatable tests to be made at multiple sites on three continents. The tests demonstrated that each imaging modality needs to be optimised for this particular application: it is, in general, not sufficient to repurpose an existing device without modification. Furthermore, it is likely that no single imaging technique will to be able to robustly detect and enable the reading of text within ancient Egyptian mummy cartonnage. However, by carefully selecting, optimising and combining techniques, text contained within these fragile and rare artefacts may eventually be open to non-destructive imaging, identification, and interpretation.

You can download and read the full article on Springer Open.

UCL Advanced Imaging Consultants (UCLAiC) undertake imaging projects on a range of heritage materials

KathrynPiquette12 January 2018

Chiddingstone Castle ancient Egyptian coffin lid, probably 25th Dynasty.

Chiddingstone Castle ancient Egyptian coffin lid, probably 25th Dynasty.

It’s been about a year and a half since UCLDH announced the establishment of UCL Advanced Imaging Consultants (UCLAiC, with a core team of Melissa Terras, Adam Gibson and myself) and began offering Reflectance Transformation Imaging and Spectral Imaging services from the UCL Multi-Modal Digitisation Suite research facility based in central London. We have since been undertaking imaging projects on a range of fascinating heritage materials. From Roman lead tablets and Egyptian mummy portraits to Persian and Mediaeval manuscripts and modern works of art, the advanced techniques we use are helping to reveal hidden writing, underdrawings and other marks that are difficult to see with the naked eye.

As we wrap up work from 2017, we are pleased to report on one of the highlights from the past years’ projects, namely multispectral imaging on a 2500-year old Egyptian coffin lid held in the collections of Chiddingstone Castle in Kent, England.

This wooden lid, shaped to represent the human form, is covered with a thin layer of yellow gesso and the head and chest are embellished with red, blue and yellow paint. A column of hieroglyphic text runs down the centre of the lid, from the brightly coloured broad collar down to the feet. Intended to ensure the sustenance of the deceased in the afterlife, this offering formula is formed of hieroglyphic signs painted in black outline with a blue-green infill. The glyphs on the foot area, however, have become very faded and damaged over time yet this is the very location where the name of the owner of the coffin would have been written.

Lower part of the coffin lid showing preserved hieroglyphic text and largely ‘invisible’ name on foot panel.

Lower part of the coffin lid showing preserved hieroglyphic text and largely ‘invisible’ name on foot panel.

Keen to learn if the name could be recovered, Chiddingstone Castle commissioned me to conduct multispectral imaging on the damaged foot area. Our multispectral system (supplied by R. B. Toth Associates), uses a medium-format, 60-megapixel PhaseOne IQ260 Achromatic camera to take a series of high-quality digital images. Illumination is provided by low heat, narrowband light emitting diodes (LED) at 12 different wavelengths from ultraviolet to near infrared, with the application of a 6-position motorised filter wheel (developed and integrated by Dr Bill Christens-Barry of Equipoise Imaging). Together with the assistance of SEAHA PhD student, Cerys Jones, the multispectral system was transported from the UCL Multi-Modal Digitisation Suite to the Castle in order to conduct the imaging onsite.

Cerys Jones and Kathryn Piquette calibrate the UCL multispectral system.

Cerys Jones and Kathryn Piquette calibrate the UCL multispectral system.

We applied 12 different wavelengths from ultraviolet to near infrared. Initial results were achieved using infrared (IR) illumination. These wavelengths, which are longer than visible light, are absorbed by carbon-based inks/paints and thus provided increased contrast between the outlines of the hieroglyphs and the surrounding surface. Thanks to the flexibility of our MSI system and Cerys’ familiarity with the specific optical properties of the pigment Egyptian blue, we tested further combinations of wavelengths and filtering. Visible induced infrared luminescence (VIL) proved vital for visualising the faint traces of paint surviving in the interior of the hieroglyphs, and we were thrilled to successfully recover the shapes of the majority of the hieroglyphs spelling out the deceased’s name.

Cerys Jones and Kathryn Piquette examine the multispectral imaging results.

Cerys Jones and Kathryn Piquette examine the multispectral imaging results.

With this image data in hand, I was able to research the name and, with the assistance of other Egyptologists, determine that the hieroglyphs most likely spell out “Irethoreru”. This name was relatively common  among males during the 1st millennium BCE and can be translated as “The Eye of Horus is against them”. The name was presumably intended to protect its bearer against his enemies, although without specifying whether these enemies were material or otherworldly. UCLAiC are pleased to have contributed to the re-discovery of the name of this ancient Egyptian who lived over 2000 years ago. This exciting work also recently appeared as part of a BBC report on UCL’s research on non-destructive technical imaging for recovering ancient hidden writing (see also: UCL News) and is also reported on the SEAHA blog.

Detail of foot panel under visible light (left), infrared (IR) illumination (middle) and visible induced infrared luminescence (VIL, right).

Detail of foot panel under visible light (left), infrared (IR) illumination (middle) and visible induced infrared luminescence (VIL, right).

While the mystery of the name has been solved, there is yet much to learn about the Chiddingstone Castle coffin lid. It was acquired by Denys Eyre Bower in the mid-20th century but unfortunately its original provenance is not known. The lid is probably part of an outer coffin that held an inner coffin which, in turn, held Irethoreru’s mummified body. One wonders whether elements of his burial equipment made their way into other UK/European museums and collections. Indeed, many Egyptian artefacts from the Third Intermediate Period and beyond (c.1000–c.300 BCE) bear the name “Irethoreru” (which may also be rendered as “Iret-hor-irou”, “Iret-horru”, “Iret-[en]-Hor-eru” or “Iretenhoreru”). Further detailed research, advanced imaging and materials analysis will be necessary to discover whether any of these funerary objects relate to Chiddingstone Castle’s Irethoreru. If you think you might have further information that could help Chiddingstone Castle learn more about their coffin lid please contact: curator@chiddingstonecastle.org.uk.

For further information about the imaging services and training courses offered by UCLDH Advanced Imaging Consultants, please visit the page or contact advancedimaging@ucl.ac.uk!

Optical coherence tomography of the first printed edition of Euclid

Lucy JStagg2 January 2018

Adam Gibson, Professor of Medical Physics and a member of the UCLDH team, has been working with Tabitha Tuckett in UCL Special Collections to see if they can find any interesting features associated with the printed diagrams in the margins of the first printed edition of Euclid’s Elements. The printer, a man called Erhardt Ratdolt, had to work out a method for printing diagrams.

Adam has written a blog post, about his findings, where you can read more about:

how modern imaging methods might be able to cast light on Ratdolt’s 500 year old printing innovation.

Optical coherence tomography of the first page of Euclid’s Elements

Optical coherence tomography of the first page of Euclid’s Elements

Imaging the first printed edition of Euclid’s Elements

Papers aplenty

Lucy JStagg28 April 2017

We’re very busy here at UCLDH, delivering papers and promoting our wonderfully diverse portfolio of research

Martin Zaltz Austwick, our Associate Director and Senior Lecturer in Advanced Spatial Analysis and Visualization, has been reporting on the Survey of London: Whitechapel project at the annual meeting of the American Association of Geographers in Boston, at a seminar for Geospatial Innovations in the Digital Humanities in Lancaster, and at a workshop on Visualizations and other digital possibilities at Birkbeck, London.

Duncan Hay, Research Associate at the Centre for Advanced Spatial Analysis, spoke at an event for World Poetry Day, organised by the Digital Scholarship team at the British Library.

Andreas Vlachidis and Antonis Bikakis will be presenting their paper on “Semantic Representation and Enrichment of Cultural Heritage Information for Fostering Reinterpretation and Reflection on the European History” at the ITN-DCH Final Conference on Digital Heritage, on 23-25 May 2017.

Pete Williams will be giving a paper at the IJAS International Conference for Academic Disciplines in Venice, on 20- 23 June 2017.

New Reflectance Transformation Imaging (RTI) training course

Lucy JStagg29 November 2016

We are rolling out our new Reflectance Transformation Imaging (RTI) training course!

Courses will take place at UCL in our Multi-Modal Digital Imaging Suite. Each course, led by Dr. Kathryn Piquette, includes a combination of lectures, demonstration, and practical hands-on sessions:

  • Learn how to apply highlight Reflectance Transformation Imaging (RTI)
  • Gain experience in applying RTI to portable objects and larger fixed surfaces of various material types
  • Become proficient in capture, processing and manipulation of RTI datasets for diverse applications
  • Gain familiarity with related computational photography and processing techniques for augmenting and re-using RTI data
  • Apply what you learn in small teams of 2-3 people for hands-on work

There is more information available, including pricing and how to register.

UCLDH Advanced Imaging Consultants

Melissa MTerras21 July 2016

UCL Centre for Digital Humanities are pleased to announce that we now have capacity to offer Reflectance Transformation Imaging and Spectral Imaging services from our Multi-Modal Digitisation Suite research facility based in central London.

Reflectance Transformation Imaging (RTI), also known as Polynomial Texture Mapping (PTM), is a high-resolution, non-invasive and non-destructive imaging technique for documenting fine surface details. Unlike conventional photographs, images created using the RTI capture method can be virtually relit. The direction of the light source can be moved around in real time to give 3D appearance to surface shapes for systematic inspection of fine surface details.

Spectral Imaging is a high-resolution, non-invasive and non-destructive form of computational photography that can disclose features of the object that are invisible to the naked eye in natural light, and can enhance faded writings, reveal palimpsest and under-drawings, as well as aiding in pigments, binders and other materials identification. Spectral imaging helps clarify and support research, scholarly and other goals. The UCL state-of-the-technology spectral imaging system can be applied to documents and manuscripts, polychrome artworks, and a range of archaeological and heritage objects.

The kinds of material we can handle and are suitable for specialist imaging include:
• Documents, manuscripts, maps
• Artworks and other painted objects
• Coins, medals, jewellery
• Other objects bearing fine details such as seals and impressed sealings, cuneiform tablets, as well as inscriptions, carvings, bas-reliefs
• Forensic evidence or any object/surface requiring detailed examination.

For further information, please see our UCLDH Advanced Imaging Consultants page or contact advancedimaging@ucl.ac.uk.