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Reflectance Transformation Imaging

By 03/03/2021April 8th, 2021News

We’ve recently been using this innovative photographic method with amazing results. Reflectance Transformation Imaging (RTI) is a multi-light imaging technique that enhances a subject’s shape and overall contrast to reveal fine surface relief.

These detailed images of a silver penny of Aethelberht of Wessex (dating to 858 – c. 862/4 AD) were captured using RTI.
A bust of Aethelberht is clearly visible on the obverse, with AETHELBEARHT REX inscribed around it. The reverse shows Moneyer’s name on, and between, the limbs of a beaded cross, with the inscription +VLEANCEA / RD / MO / N / E / T / A

Multiple photographs are taken from one position, with the surface of the subject illuminated from different angles in each image. Software is then used to compile information from surface texture and degree of reflectance. The resulting output can then be interactively re-lit, to produce varying highlights and shadows which disclose fine detail. This method can be used on structures with graffiti, rock art, and even paintings.

This comparatively sad looking image shows how the coin appears to the naked eye.

As well as revealing much greater detail, RTI will allow our finds specialists and other researchers to examine and study the coin without having to physically handle the object.

This RTI was done by the Cambridge Office’s Archivist, Ryan.