Fig. 3.

Kelvin temperatures of different LED devices. Correlated color temperature measures degrees Kelvin indicating the different hues of light sources emitted by an idealized, opaque, non-reflective body. Color temperature ranges from warm to cool, along a locus correlating infrared light (at $\sim 100\mathrm{K}$) to ultraviolet light (at $\sim \mathrm{50,000}\mathrm{K}$). Blue occurs at higher Kelvin temperatures, and red occurs at lower Kelvin temperatures, which is the inverse of what is visually expected from “warm/cool” colors. In between the two extremes lies halogen ($\approx 3000\mathrm{K}$), daylight ($\approx 5500\mathrm{K}$), xenon ($\approx 6200\mathrm{K}$), and LEDs (variable K). Shown here are three LED dermoscopes and their relative position on the Kelvin Chart, as well as a halogen dermoscope and the LED from an iPhone for comparison.