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Kelvin-Scale
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The correlated color temperature of HID headlamp bulbs, at between 4100K and 4400K, is often described in marketing literature as being closer to the 6500K of sunlight compared with tungsten-halogen bulbs at 3000K to 3550K. Nevertheless, HID headlamps' light output is not similar to daylight. The spectral power distribution (SPD) of an automotive HID headlamp is discontinuous, while the SPD of a filament lamp, like that of the sun, is a continuous curve. Moreover, the color rendering index (CRI) of tungsten-halogen headlamps (≥0.98) is much closer than that of HID headlamps (~0.75) to standardized sunlight (1.00). Studies have shown no significant safety effect of this degree of CRI variation in headlighting. |
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