Luminance vs Illuminance

Luminance and illuminance are two very important concepts discussed in physics. Luminance is the amount of light energy that is produced by a surface or an object. Illuminance is the amount of light energy incident on a given surface. The concepts of luminance and illuminance are widely used in fields such as physics, photography, chemistry, engineering, astronomy, astrophysics and numerous other fields. In this article, we are going to discuss what luminance and illuminance are, the definitions of luminance and illuminance, the units of measurement used in measuring luminance and illuminance, their applications, and finally the comparison of luminance and illuminance.

What is Luminance?

The definition of luminance is the amount of light emitted, passing through or reflected from a surface. Think of a lamp shining in a dark room — luminance would describe the amount of the light passing through the lightbulb.

Luminance is often used interchangeably with the term brightness. However, when it comes to luminance vs. brightness, these descriptions are not interchangeable. Luminance is a quantifiable, measurable characteristic. Whereas brightness cannot be objectively measured — it can only be perceived. We recognize that a light source is bright or dim, making brightness the visual sensation by which we become aware of differences in luminance.

When it comes to color decisions for your business, luminance can also describe a certain color’s perceived brightness.

What is Illuminance?

Illuminance is a term which is often misinterpreted as luminance or luminosity. Illuminance measures the amount of light incident on a surface. In other words, illuminance measures the amount of light illuminating the surface. This is weighted by the wavelength, to compensate for the sensitivity of the human eye. Illuminance is defined as the total luminance flux incident on a given surface per unit area.

Illuminance is measured in either lux or lumens per square meter. The SI unit of illuminance is

Illuminance is widely used in photography to measure the light illuminating the surface being photographed. Too much illuminance will wash out all the details from a surface while too little illuminance will be hard to detect.


What is the difference between luminance and Illuminance?

• Luminance is a quantity which identifies the amount of light emitted from a surface whereas illuminance is a quantity which identifies the light illuminating the surface.

• Luminance depends on the nature and properties of the surface whereas illuminance of a surface does not depend on the nature of the surface.

Post time: Mar-24-2022
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