Recent advances in x-ray imaging and image processing are providing new options for the nondestructive physical evaluation of archaeological artifacts and works of art. Traditional film-based methods have played an important role in this field for many decades1, but digital modes developed for medical and industrial applications have been gaining ground2 and can be expected to become more important as they become more accessible and less expensive. Modes such as digital radiography (DR) and computed tomography (CT) have many advantages in terms of information content, quantitative analysis options, and image display options (including some that make image publication easier). CT, in particular, provides structural information which cannot be obtained through any other nondestructive means. From a technical point of view, the only real drawback to digital methods has been spatial resolution that hasn't compared favorably with the best available from film. That situation is changing3.
The objective here is to discuss a few of the important characteristics peculiar to digital images, to show examples of how high-resolution digital images can provide important structural information, and to illustrate useful types of image processing. The use of experimental CT and DR systems, with spatial resolution as fine as 50 microns, is illustrated in studies of three objects: an ancient terracotta sculpture, a Japanese assembledwoodblock sculpture (ca. 17th century), and an oil painting on canvas (ca. 18th century).