Characterization of crosstalk in high-resolution active-matrix liquid crystal displays for medical imaging

In active-matrix liquid crystal displays with large pixel array and large number of graylevels, the luminance of a pixel depends on the luminance of the rest of the image. This artifact known as crosstalk is caused by parasitic phenomena in the active-matrix array. When interpreting high information content medical images with subtle features and structured background, crosstalk can affect image fidelity and diagnostic performance. Conventional methods rely on the measurement of the luminance change of small square targets located across the screen when changing the background intensity. We present a method that describes both the magnitude and the spatial extent of the crosstalk artifact. The method is based on the formulation of a response function that corresponds to the differential contribution of a vertical or horizontal line to the luminance of a small centered target. The response function is defined for a given screen position, along the horizontal or vertical display axis. Our measurements show that subtle differences between vertical and horizontal crosstalk can be detected with the proposed method, and that most of the influence is confined to a 40-pixel region about the target. The results obtained with the proposed characterization method allow for the modeling of crosstalk effects to determine its impact on a variety of visual tasks.