Abstract
Landolt C visual acuity of eight subjects was measured as a function of stimulus luminance. To simulate traffic sign viewing, a stimulus field width of 0.7º with a surround field of 60º was used. The surround luminance was changed in steps of a factor of 10 from 0, 5 to about 5000 cd/m2. Both dark symbols on a light background and light symbols on a dark background were considered. The presentation time was either unlimited or 200 msec.