Artificial Lighting

White light ranges from cool to warm

Cool light contains more blue light and is what can be expected from cheap Light Emitting Diode lighting.

Warm or soft white light contains more red light (the less energetic part of the spectrum).

Colour rendering is controlled by the mix of phosphors in a Compact Flourescent Lamp.

Although the lumen output per watt for CFLs is similar to LEDs, the useful lumens produced by LEDs are far greater.

Useful lumens are the ones emitted within a 120° cone.