Influence of film and monitor display luminance on observer performance and visual search

Rationale and Objectives. The purpose of this study was to measure the infl uence of display luminance on detection performance and visual search behav ior. The results of the study should be helpful in establishing minimally a cceptable display conditions for viewing radiographs on cathode-ray tube (C RT) monitors. Materials and Methods. Two groups of six radiologists each viewed 50 pairs of mammograms. One group viewed film images on a standard mammographic view box; the other viewed images on a high-resolution CRT monitor. Two luminan ce levels were studied for each display type. Observers reported on the pre sence or absence of masses or microcalcification clusters and on their conf idence in that decision. Confidence data were analyzed by using alternative free-response receiver operating characteristic (AFROC) techniques. Eye po sition also was recorded as observers viewed the images. Results. For both the film and monitor studies, detection performance (AFRO C area under the curve) was not affected significantly by display luminance , but search behavior was. Total viewing and decision dwell times were shor ter with the higher-luminance displays, especially for true-negative decisi ons. Significantly more fixation clusters were generated during the search of lesion-free than of lesion-containing images with the lower-luminance di splays. Conclusion. Display luminance affects visual search performance with both f ilm and monitor displays without affecting detection performance significan tly. Higher-luminance displays yield more efficient search performance. The true-negative dwell times and number of clusters are suggestive that lower -luminance levels prolong the search and recognition of normal, lesion-free areas compared th lesion-containing areas.