June 2006
Volume 6, Issue 6
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2006
Calibrated LCD stimulus presentation for visual psychophysics in fMRI
Author Affiliations
  • Hans Strasburger
    Dept. of Medical Psychology, Georg-August University Göttingen
  • Torsten Wüstenberg
    Dept. of Medical Psychology, Georg-August University Göttingen
Journal of Vision June 2006, Vol.6, 71. doi:10.1167/6.6.71
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      Hans Strasburger, Torsten Wüstenberg; Calibrated LCD stimulus presentation for visual psychophysics in fMRI. Journal of Vision 2006;6(6):71. doi: 10.1167/6.6.71.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Standard stimulus presentation techniques using liquid crystal (LCD) or cathode-ray tube (CRT) technology show drastic distortions in luminance and contrast characteristics across the screen and across gray levels. Common gamma-correction does not address screen inhomogeneity. Moreover, the common luminance measurement and calibration techniques are not applicable in the vicinity of an MRI scanner. With the aid of a fiber optic, we measured in our monitor screen luminances for the full space of screen position and image gray values. On that basis we developed a compensation technique that involves both luminance homogenization and position-dependent gamma correction. For fine resolution across the screen, the technique uses interpolation of gamma-curve coefficients rather than the luminance interpolation used elsewhere and thus achieves high precision with fewer parameters. Implemented in MATLAB® the calibration can be applied to both images and movies. By the technique described, images displayed to a subject in functional MRI can be specified with high precision by an image matrix of target luminance values rather than by local gray value.

Strasburger, H. Wüstenberg, T. (2006). Calibrated LCD stimulus presentation for visual psychophysics in fMRI [Abstract]. Journal of Vision, 6(6):71, 71a, http://journalofvision.org/6/6/71/, doi:10.1167/6.6.71. [CrossRef]
Footnotes
 Work supported by DFG grant STR 354/3-1 to H. Strasburger
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