Improvements in the Acquisition and Processing of X-ray Images of Paintings
Joseph Padfield, David Saunders, John Cupitt and Robert Atkinson
Technical Bulletin Volume 23, 2002
The history of x-radiography of paintings throughout the 20th century is summarised. Film type and exposure conditions used in recent years are detailed. Until recently, roughly A3-sized film was used, an internegative was made, and then the developed photographs were hand-assembled into a life-size X-ray mosaic. Now the processed films are scanned with a large flat-bed scanner and mosaicked with Virtual Instrument Presentation Software (VIPS). Plates have to be rotated, scaled, and translated by the software to correct for the finite thickness of a painting and the general unevenness of the paint film when X-ray plates are spread over it. The 'tie points' to match one plate to the next must be selected by a human operator, because of these geometrical distortions, as the mosaic is assembled. Software has been created to model the effect of a cradle on a panel and to give a mosaic uninterrupted by the secondary support. Other techniques for dealing with this are discussed.
computer modelling, digitising, paintings, radiography, software
To cite this article we suggest using
Padfield, J., Saunders, D., Cupitt, J., Atkinson, R. 'Improvements in the Acquisition and Processing of X-ray Images of Paintings'. National Gallery Technical Bulletin Vol 23, pp 62–75.
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