In February 1987, after $3 million and five years of development by the Jet Propulsion Laboratory and the Perkin-Elmer Company, the U. S. National Archives and Records Administration installed a charge coupled device (CCD) camera and image processing system to monitor the physical condition of the U.S. Constitution. The system, called the Charters Monitoring System, is capable of comparing the pattern of one image with another to facilitate the detection of any changes that may be occurring on the document. To assure that the difference between images are not due to variations in illumination, CCD response, or position of the camera, the Charters Monitoring System must precisely control illumination, (including its intensity, alignment, and stability), CCD (including temperature, dark current, charge transfer control, gain correction, and integration time), camera focus, resolution, registration, and consistent analog to digital conversion. The system offers examples of precision and accuracy problems in electronic imaging and the importance of repeatable image capture relative to quality control of electronically produced images.