Using a human visual system model to optimize soft-copy mammography display: influence of veiling glare

RATIONALE AND OBJECTIVES: This project evaluated human observer performance and that of a human visual system model (JNDmetrix) to assess whether the veiling glare of a digital display influences observer performance during soft-copy interpretation of mammographic images for the detection of masses. MATERIALS AND METHODS: A set of 160 mammographic images, half containing a single mass, was processed to simulate four levels of veiling glare: none, comparable to a medical grade monochrome curved-screen cathode ray tube (CRT) display, double that of the CRT and quadruple that of the CRT. The images were shown to six observers in a randomized presentation order on a liquid crystal display (LCD) that had essentially no veiling glare. The images were also analyzed using the JNDmetrix human visual system model. RESULTS: Observer performance as measured using receiver operating characteristic techniques declined with increasing veiling glare (F = 6.884, P = .0035), with quadruple veiling glare yielding significantly lower performance than the lower veiling glare levels. The JNDmetrix model did not show a large reduction in performance as a function of veiling glare, and correlation with the human observer data was modest (0.588). CONCLUSIONS: Soft-copy display veiling glare can influence observer performance, but only at extreme levels. The impact of veiling glare on performance may be more pronounced for less experienced readers.