Abstract
Nine types of resolving-power test-object patterns were compared with the tricolumnar type that has been used for many years in these Laboratories. A high-speed, low-contrast film designed for aerial photography was used for all the patterns studied while two patterns were also photographed on a fine-grain, high-contrast film used for microcopying printed matter. All the columnar patterns read practically the same as the tricolumnar one when the line lengths were comparable; when the lengths were less than those of the tricolumnar pattern or when the patterns were of other shapes, lower readings were obtained than for the tricolumnar pattern. This pattern itself gave lower values when the lines were shortened. The Landolt broken-circle pattern was found to be promising for evaluating the ultimate detail-rendering power of an emulsion as distinguished from its resolving power in lines per unit distance. The luminance ratio between the characters and the background of the tricolumnar test object was varied, and it was found that the effect on the resolving power depended upon the emulsion. When resolving power was plotted against the reciprocal of the luminance ratio, the relation was rarely a straight line that would indicate an exponential relation between resolving power and luminance ratio itself; the departures from linearity were similar qualitatively for most materials but different quantitatively. The trend for a given material appeared not to be greatly altered by a considerable change in development conditions.
© 1953 Optical Society of America
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