Illuminance

Illuminance image

In photometry, illuminance is the total luminous flux incident on a surface, per unit area. It is a measure of how much the incident light illuminates the surface, wavelength-weighted by the luminosity function to correlate with human brightness perception. Similarly, luminous emittance is the luminous flux per unit area emitted from a surface. Luminous emittance is also known as luminous exitance.In SI derived units these are measured in lux (lx), or equivalently in lumens per square metre (lm·m−2). In the CGS system, the unit of illuminance is the phot, which is equal to 10000 lux.

Luminance
4 months ago

Luminance ... luminous power is concentrated into a smaller area, meaning that the illuminance is higher at the image. The light at the image plane, however, fills...

Lux
4 months ago

Lux ... The lux (symbol: lx) is the SI derived unit of illuminance, measuring luminous flux per unit area. It is equal to one lumen per square metre. In photometry...

Kruithof curve
5 months ago

Kruithof curve ... The Kruithof curve describes a region of illuminance levels and color temperatures that are often viewed as comfortable or pleasing to an observer. The...

Daylighting
4 months ago

Daylighting ... daylight received in an internal space can be analyzed by measuring illuminance on a grid or undertaking a daylight factor calculation. Computer programs...

Candela
5 months ago

Candela ... this area, illuminance at point  r  on  d A ,  E v ( r ) = ∑ i | a ^ ⋅ ( r − r i ) | | r − r i | 3 I i . {\displaystyle {\text{illuminance at point }}\mathbf...

Solar constant
4 months ago

Solar constant ... The solar constant (GSC) is a flux density measuring mean solar electromagnetic radiation (solar irradiance) per unit area. It is measured on a surface...

Exposure value
4 months ago

Exposure value ... luminous/photometric exposure E is the image-plane illuminance t is the exposure time ("shutter speed") The illuminance E is controlled by the f-number but also...

Lumen (unit)
5 months ago

Lumen (unit) ... square metre with an illuminance of 1000 lux. The same 1000 lumens, spread out over ten square metres, produces a dimmer illuminance of only 100 lux. Mathematically...

Light meter
1 month ago

Light meter ... slightly revised definition of illuminance, measurements with a hemispherical receptor indicate “effective scene illuminance.” It is commonly stated that...

Daylight
1 month ago

Daylight ... explanation of why it is not exactly half, see here). However, the outdoor illuminance can vary from 120,000 lux for direct sunlight at noon, which may cause...

Photometer
5 months ago
UEFA stadium categories
4 months ago
Orders of magnitude (illuminance)
3 months ago
Sunlight
4 months ago
Exposure (photography)
4 months ago
Brightness
4 months ago
Surgical lighting
3 months ago
Transflective liquid-crystal display
1 month ago
Solar eclipse
1 month ago
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