Light illumination is the amount of light illuminating a point on a surface. Illuminating sources can be natural (daylight) or from lamps, lighter, etc.
In SI, derived unit of illuminance is lux (lx) and equals to a meter candle. It means, illuminance on a surface is one candela source per meter. Foot candle
(lumen per square foot) is a non-SI unit of illumination. 1 foot candle (fc) equals to 10.76 lux.
Other common units to measure the illumination are meter candle, flame, lumen per square meter, nox, phot and watts per square centimeter.
For luminance conversions please goto Luminance Conversion
For luminous intensity conversions please goto Luminous Intensity Conversion