the intensity of illumination in the SI units is that for on the unit level is defined. Every luxury is equivalent to one Lumen on a square meter. In the sciences, photometry, etc. luxurious as the scale to measure the light intensity by the human eye understand can be used. This unit in science equivalent unit Watt on square meter., but in the luxury of any length of wave a weighted is according to the function, luminance can be calculated. Function luminance or curve the sensitivity of the eye or the function of optical efficiency, a function, or curve, that is, the average sensitivity of the human eye to light at various wavelengths specified.