Science and Heritage Programme

Seeing Through Walls: Discovering Europe's Hidden Mural Paintings

University of Reading

Dr Gillian Walker


Seeing Through Walls: Discovering Europe's Hidden Mural Paintings

University of Reading

Dr GC Walker
Amount awarded: £281,055.00

The aim of this research proposal is to visualise wall paintings which have been obscured under layers of plaster and paint using a portable pulsed terahertz imaging system. Unlike other technologies used to study wall paintings, terahertz radiation is able to penetrate millimetres of plaster and still detect the obscured picture, while also providing spectral information which can be used to identify the shade and in some cases the age of the wall painting pigment and the covering plaster. Terahertz radiation is non-ionising and non-destructive and will in no way affect the integrity of the artefact under investigation.

Uncovering obscured paintings will be of huge cultural significance to the communities in which they lie dormant. They provide key information about the host building's evolution and influence on the wider community as well as art heritage.

An output of this work would be a multifunction, user orientated, software package to generate numerous 2D and 3D terahertz images, based on properties of the reflected radiation, the physical properties of the pigments used to paint the image, the physical properties of the covering plaster, and thickness of the constituent layers of the wall painting. There will be facilities to generate enhanced spatial resolution at key boundaries in the image and to correct for non-Gaussian noise introduced by uneven plaster surfaces. Optimum image reconstruction methodologies will be identified combining these features. This software will be aimed at non-specialist terahertz users and it is hoped it will be key to integrating the technology with the art heritage community. Commercial aspects of the software will be exploited.

Work will begin using mock wall paintings and will be developed to culminate in testing on actual artefacts. The Centre for Research and Restoration, The Louvre, Paris will provide access to artefacts including fragments of obscured Botticelli paintings housed at the Louvre and access to other obscured paintings in their place of origin across Europe.

Underpinning this software will be key theoretical descriptions of the terahertz radiation as it is reflected from the wall painting and a unique Systems Identification approach which will be taken to solve the terahertz inverse problem. This work will produce fundamental papers for the terahertz research community, essential for the development of terahertz imaging as a generic imaging modality. This work will be, in some cases almost directly, transferable to other application areas.