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Abstract
The use of a charge-coupled device (CCD) camera for monitoring the condition of valuable documents, such as the U.S. COnstitution, is described. The behaviour of the CCD, characteristics of illumination, and camera positioning are accurately controlled to produce images that can be compared with other images obtained in precisely the same way. Comparisons of these images provide the basis for determining if any changes have taken place. The control of variables for precision and accuracy provide examples of quality control criteria for electronic images.