Display Evaluation Report - A Survey of Five 5-MegaPixel Monochrome CRT Monitors for Medical and Government Imaging Applications

摘要

Measurements of the performance of five, high-brightness, monochrome, 21-inch viewing diagonal, portrait, CRT monitors with addressability of 2,048 x 2,560 pixels have been conducted, analyzed, and reported in accordance with consistent metrological practices developed by the NIDL. In terms of two performance metrics, the number of 'resolvable pixels on grayscale imagery' and peak luminance, the monitors range in performance from 2.9 to 5.2 million pixels and from 240 candelas per square meter (70 footLamberts) to 514 cd/m2 (150fL). Although each monitor can address 2,048 x 2,560 pixels, each monitor achieves a different number of resolvable pixels because of differences in the size of the scanned electron beam spot at the phosphor screen. Measurements of the spot shape and size were conducted and plotted on the same scale to facilitate comparison. The range in peak luminance arises from the range in transmission of the CRT faceplate glass (30% to 50%), the efficiency of the phosphor screen, and the peak beam current the CRT and monitor circuitry were specified to operate at. Given a number of monitors all matched in peak brightness, those with low faceplate glass transmission are expected to provide visibly-higher contrast in brightly-lit viewing environments and, therefore, to better enable people to detect low-brightness, low-contrast detail in images. Given a number of monitors of the same peak brightness and transmission and under the same ambient lighting, those with a larger number of resolved pixels will provide a sharper looking image that better enables detection of detail. Given a number of monitors with the same transmission and resolvable number of pixels and under the same ambient lighting conditions, those with higher peak luminance and, therefore, higher dynamic range, are expected to better enable the detection of low-brightness, low-contrast pixels or small clusters of pixels in an image.