Characterization of a high-quality monochrome AM-LCD monitor for digital radiology

In this paper, we present results concerning the development of advanced characterization methods and their application to the evaluation of a high-end medical imaging monitor. The display is a 20.8-inch diagonal high-resolution (2048 x 1536 pixels, 123 dpi) monochrome active-matrix liquid-crystal display (AM-LCD) based on a-Si:H TFT active-matrix, dual- domain and in-plane switching technologies. We report the luminance characteristics of the AM-LCD, its grayscale performance, and the panel deviation from the DICOM standard grayscale function. The display luminance for different gray levels under both normal and off-axis viewing directions is described, together with the resulting contrast ratio. The viewing angle dependence of the luminance and contrast ratio is also studied in terms of display compliance to DICOM's grayscale function at off- normal viewing angles. Small-spot contrast ratio performances are investigated in relation to the display technology and especially parasitic phenomena such as electronic crosstalk. We also present the effect of target size and luminance on small-spot contrast ratio results, and we report the orientation dependence of this phenomenon. In addition, we present results on reflections, spatial resolution and display noise and texture and the AM-LCD performances are compared to typical parameters obtained for medical imaging CRTs.