A study on lighting uniformity for LED smart lighting system

A psychophysical experiment was conducted to study lighting uniformity across a desk top and the wall as well. The data were used to evaluate three uniformity metrics. Four attributes were scaled including uniformity, comfort, brightness and contrast perceptions using a categorical judgment method. Twenty-one subjects were asked to rate the attributes under different degree of lighting uniformity. The results showed that using the ratio between minimum and average to evaluate the uniformity performed the best, and a ratio of between 0.80 and 0.90 were consistently to provide accepted comfort across the desk top. Also, the contrast of lighting is significantly negatively correlated with uniformity. In the same illuminance level, more uniform lights will make subjects feel more comfortable. And in the same uniformity level, brighter lights will also make subjects feel more comfortable. Different desk tops and different illuminance levels will not significant influence the uniformity perception.