Color Perception and Recognition under Automotive Headlight with LED

In the near future, the LED headlamps will be available in the market by improvement of the technique. There are some methods that can produce white light using LEDs. Probably, we think most generally method is using blue LED and yellow phosphor. But, spectral power distribution (SPD) of this type of white LED is much different from traditional white light that is produced by halogen or HID. This type of the white LED has poor spectral power in long wavelength region and much spectral power in short wavelength region. So, the white light by LED might have color-rendering problem. On the assumption that automotive head lamps with white LED and halogen, the human color perception and recognition under wide range of illuminance conditions from photopic to mesopic was measured, using categorical color naming method and elemental color scaling method. As the result of this measurement, stability of categorical color naming was lower under lower illuminance level with both light sources. However, stability of categorical color naming of safe colors, which is using of road signs, was higher under various illuminance levels with both light sources.