myERCO
myERCO
Your free myERCO account allows you to mark items, create product lists for your projects and request quotes. You also have continuous access to all ERCO media in the download area.
You have collected articles in your watchlist
Technical environment
Technical environment
Global standard 220V-240V/50Hz-60Hz
Standard for USA/Canada 120V/60Hz, 277V/60Hz
  • 中文

Our contents are shown to you in English. Product data is displayed for a technical region using USA/Canada 120V/60Hz, 277V/50Hz-60Hz.

More user friendliness for you
ERCO wants to offer you the best possible service. This website stores cookies for this purpose. By continuing to use this website, you consent to the use of cookies. For more information, please read our privacy policy. If you click on "Do not agree", essential cookies will continue to be set. Certain contents of external pages can no longer be displayed.

Luminance: definition and unit of measure

Figure depicting luminance.

The luminance L of a self-luminous surface results from the ratio of luminous intensity l and its projected area Ap.

Luminance (L) describes the brightness perceived by the human eye of a surface that, as a light source or through transmission or reflection, emits light. Luminance is defined as the ratio of luminous intensity (I) to the area projected perpendicular to the direction of observation (Ap). The photometric unit is candela per square foot meter (cd/ sq ft)

Would you like to find out more?

What is luminance?

While illuminance (E) is the light incident on a surface, the luminance (L) describes the light radiating from this surface. The light can radiate from the surface itself, for example from a lamp, but it can also be reflected or transmitted from a surface. For diffuse reflecting (matt) and diffuse transmitting (opaque) materials, the luminance can be calculated from the illuminance and the reflectivity- or transmittance factor.

Luminance thus forms the basis of the perceived brightness; however, the actual impression of brightness is still influenced by the state of adaptation of the eye, the peripheral contrast ratios and the information content of the surface seen.

Interesting!

Luminance is the only photometric parameter perceived directly by the human eye.

Would you like to find out more?

Further topics on photometry

Do you need further information?

You can contact your regional contact partner via:

You can gladly send us an e-mail or ask your question here

Your data will be handled confidentially. For further information see Data protection declaration.

ERCO Newsletter - inspiring projects, new products and fresh lighting knowledge

Subscribe to the newsletter
Your data will be handled confidentially. For further information see Data protection declaration
From now on, for convenience and speed, we will be emailing the ERCO Newsletter in a digital format on a regular basis to help you keep up with the latest news from ERCO. We aim to ensure that you’re updated about events, awards, fresh lighting knowledge, project reports and product news along with reports from the lighting and architectural sectors. The publication is free and you can unsubscribe at any time.