T3D acuity enhanced......display issues

[Peter Abrahams <telscope@xxxxxxxxxx>]

>Did the paper discuss any methods used to allow for
>display-related issues?

>From the article:
Our computerized acuity test system overcomes the limitations of printed
letter charts by permitting control of contrast and by randomizing letter
combinations to permit within-subject repeated testing and thus higher test
reliability.
Sloan characters were displayed on a Mitsubishi color monitor driven by an
X-Windows (X-11) server residing on a Silicon Graphics IRIS 4D/25 graphic
workstation with a StereoGraphics Corporation stereo-display system.  The
final resolution of the display was 1280 horizontal x 512 vertical pixels,
and the luminance was 88.3 cd/m^2.  ....(low vert. from synced
shutters....monitor 120Hz..)The glasses provided an apparently flicker-free
60-Hz image to each eye, with 32% transmittance and negligible cross talk
(~1.1% transmittance through the closed shutter)  
The letter sizes that we used ranged from 2.2 to 0.43 cm.
(...viewed through backward binoculars)...The resulting optical distance of
950cm....permitted us to test acuities in the range of 0.2 to -0.5 log
minimum angle of resolution (MAR) (20/32 to 20/6.3 Snellen equivalent).
The luminance of the screen, after attenuation by both the shutter glasses
and binoculars, was ~18cd/m^2....(only light in dark room.)
We used four contrast levels...0.313, 0.465, 0.679, and 0.994.  Contrast
between the foreground (character) luminance Lfg and the background
luminance Lbg was defined as Lbg - Lfg / Lbg.  We varied contrast.by
changing only the foreground luminance.
For the monocular condition background luminance was presented to one eye
while the other eye received letters at each of the four contrasts.

______________________________________
Peter Abrahams, telscope@xxxxxxxxxx


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