brighteness

Brightness is a perceptual property of visual perception, describing the luminous intensity of a light source or the luminous emittance of a surface. It is how an observer perceives the intensity of light. In scientific contexts, brightness is often quantified using luminance, a photometric measure of the luminous intensity per unit area of light traveling in a particular direction. Luminance is measured in candelas per square meter (cd/m²) or nits.

Subjectively, brightness can be influenced by various factors beyond the objective amount of light. These include the color of the light, the surrounding environment, and the adaptation state of the observer's eyes. For instance, a dimly lit room can make a moderately bright object appear very bright, while the same object in direct sunlight might seem dim. Color also plays a role; the human eye is more sensitive to certain wavelengths of light, affecting our perception of brightness.

In digital displays and lighting technology, brightness is a key parameter controlled by adjusting the intensity of light emitted. This is often achieved by altering the power supplied to light sources or by modulating the duration or frequency of light pulses. Understanding brightness is crucial in fields ranging from photography and filmmaking to astronomy and the design of lighting systems. It directly impacts how we see and interpret the world around us.