X-radiography is used for the structural examination of art and artifacts, as it is used by doctors in hospitals. For art works, it helps to reveal losses, replacements, and methods of construction that may not be visible to the naked eye. X-rays are a form of high energy electromagnetic radiation that travel like ordinary light but can penetrate through most objects. The amount of x-ray intensity absorbed by the object depends on the density and thickness of the material. Since denser areas absorb more x-rays, the film receives less exposure and the corresponding areas appear lighter.
Xeroradiography is an alternative method of recording X-ray images .
The plate is then processed through a unique photocopying-type machine. The recorded image of the interior of the object is then transferred onto plastic-coated paper. The denser elements appear darker by xeroradiography.