The term resolution, in the context of photography, refers to the degree to which adjacent objects can be distinguished from one another in a photographic image. Obviously, the higher the degree of resolution—which is a function of the acuity of the photographic equipment used, as well as the abilities of the operator—the better the quality of the photograph. The lower the figure given for the resolution, in metric or English units, the higher the degree of resolution.
For example, the first four satellites of the CORONA project, which remained aloft throughout most of the period from June 1959 to December 1963, had a relatively high resolution of 25 feet (7.6 m), meaning that objects smaller than that size were likely to be indistinguishable from one another. Higher still was the resolution of the fifth satellite in the series, KH-4B (September 1967-May 1972), at 6 feet (1.8 m). Photographs taken by KH-5, a satellite deployed for mapping purposes between February 1961 and August 1964, had a much lower degree of photographic resolution: 460 feet (140 m).
█ FURTHER READING:
Williams, John B. Image Clarity: High-Resolution Photography. Boston: Focal Press, 1990.
Declassified Intelligence Satellite Photographs. < http://mac.usgs.gov/isb/pubs/factsheets/fs09096.html > (February 13, 2003).