1997 Volume 81 Issue 5 Pages 392-397
We carried out the psychophysical experiment matching and comparing the intensity of a flash light with that of a fixed light, because some papers have reported that the formula for the effective intensity of a flash light presented by Blondel & Rey in 1912 can not be applied when the background is bright and when the luminance exceeds a certain threshold.
As a result of this experiment, we propose that the effective intensity of a flash light when background condition is 0 cd/m2 he exuressed by
loge (Y) = [-4.4+0.88×loge (X)] +0.7× loge (T)
Y: Effective intensity of a flash light in lx.(Illuminance of a fixed light at the observer's eye in lx.)
X: Illuminance of a flash light at the observer's eye in lx.
T: Lighting time period in msec.