Effect of viewing angle response on DICOM compliance of liquid crystal displays

Ehsan Samei; Steven L. Wright

doi:10.1117/12.536198

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19 April 2004 Effect of viewing angle response on DICOM compliance of liquid crystal displays

Ehsan Samei, Steven L. Wright

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Proceedings Volume 5371, Medical Imaging 2004: PACS and Imaging Informatics; (2004) https://doi.org/10.1117/12.536198
Event: Medical Imaging 2004, 2004, San Diego, California, United States

Abstract

Cathode-ray tube (CRT) and liquid crystal display (LCD) are currently two main technologies for displaying medical images. LCDs possess a number of advantages, but their performance varies as a function of viewing angle. The purpose of this study was to delineate the impact of the angular response of LCDs on their DICOM grayscale display function (GSDF) compliance, and to develop a framework to define an angular acceptance for medical LCDs. Measurements were made on a calibrated dual-domain LCD (IBM T221). The on-axis luminance values were measured at all 8-bit driving levels three times using the TG18-LN test patterns and a baffled luminance meter and the results averaged. The luminance was also measured as a function of viewing angle at 17 discrete levels using a Fourier-optics-based luminance meter. The luminance data were analyzed according to the AAPM TG18 methodology. The on-axis results showed close conformance with the TG18 criteria with L_min, L_max, mean ▵JND/▵p, and maximum local deviation in ▵JND/▵p from GSDF, &kappa²⁵⁶, of 0.83 cd/m², 263 cd/m², 2.1, and 0.8, respectively. However, the values varied notably as a function of viewing angle. Overall, the luminance ratio remained greater than 175 within a ±20° viewing angle cone (β₁₇₅ = ±20°). Aiming to maintain κ¹⁷≥0.3, an acceptable viewing angle cone of ±35° was indicated (α_0.3 = ±35°). The findings demonstrate the significant impact of angular response on image contrast, and the utility of α_0.3 and β₁₇₅ quantities for defining the viewing angle cones within which a medical LCD device can be effectively utilized.

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Ehsan Samei and Steven L. Wright "Effect of viewing angle response on DICOM compliance of liquid crystal displays", Proc. SPIE 5371, Medical Imaging 2004: PACS and Imaging Informatics, (19 April 2004); https://doi.org/10.1117/12.536198

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