Effect of Viewing Angle on Luminance and Contrast for a Five-Million-Pixel Monochrome Display and a Nine-Million-Pixel Color Liquid Crystal Display
Digital imaging systems used in radiology rely on electronic display devices to present images to human observers. Active-matrix liquid crystal displays (AMLCDs) continue to improve and are beginning to be considered for diagnostic image display. In spite of recent progress, AMLCDs are characterized by a change in luminance and contrast response with changes in viewing direction. In this article, we characterize high pixel density AMLCDs (a five-million-pixel monochrome display and a nine-million-pixel color display) in terms of the effect of viewing angle on their luminance and contrast response. We measured angular luminance profiles using a custom-made computer-controlled goniometric instrument and a conoscopic Fourier-optics instrument. We show the angular luminance response as a function of viewing angle, as well as the departure of the measured contrast from the desired response. Our findings indicate small differences between the five-million-pixel (5 MP) and the nine-million-pixel (9 MP) AMLCDs. The 9 MP shows lower variance in contrast with changes in viewing angle, whereas the 5 MP provides a slightly better GSDF compliance for off-normal viewing.
KeywordsActive-matrix liquid crystal display (AMLCD) viewing angle gray-scale display function (GSDF)
- 1.American College of Radiology/ National Electrical Manufacturers Association: Digital Imaging and Communications in Medicine (DICOM), Part 3.14, Grayscale Standard Display Function. Technical report, ACR/NEMA, January 1998Google Scholar
- 4.Badano, A, Fifadara, DH 2004Comparison of conoscopic, telescopic, and goniometric methods for measuring angular emissions from medical liquid-crystal displaysAppl Optics..Google Scholar
- 6.E. Samei A, Badano D, Chakraborty K, et al.: Assessment of display performance for medical imaging systems. Draft Report of the American Association of Physicists in Medicine (AAPM) Task Group 18. Technical report, AAPM, October 2002Google Scholar