Exposure vs Brightness
Brightness and exposure are two of the main topics discussed in photography. Exposure is the amount of light to which a photograph or a video is exposed. Brightness is a property of the final photograph which tells how “bright” the photo appears. These concepts are widely used in photography, videography, astronomy, physics, instrumentation and numerous other fields. It is very useful to have a proper understanding in these terms in order to excel in such fields. In this article, we are going to discuss what exposure and brightness are, their definitions, applications, relationship between exposure and brightness, and finally the difference between exposure and brightness.
Brightness
Brightness is a very important quantity discussed in photography and astronomy. In photography, brightness is the luminance effect created by a light source or reflected light. Brightness is formally defined as the energy carried by electromagnetic waves going through a unit area per time. Brightness is a visual perception which enables the observer or the viewer to see an image as bright or dark. A light source or a light reflector is considered as a bright spot whereas a light absorbing surface is known as dark.
The brightness is often quantified using the RGB scale. RGB scale, which stands for Red, Green, Blue scale, is a three dimensional color space where any color can be quantified using the R, G, and B values of the color. The brightness, often denominated using the symbol µ is quantified as,
µ=(R+G+B)/3, where R, G, and B are corresponding Red, Green, and Blue values.
In astronomy, brightness is divided into two types. Apparent magnitude is the brightness of a star observed from a given location. Absolute magnitude is the brightness of a star observed from 10 parsecs (32.62 light years).
Exposure
Exposure is a property discussed mainly in photography. Exposure level on a photograph depends on several factors. The shutter speed is one of the factors that control the exposure. Slower the shutter speed, higher is the exposure level. Aperture size is the other controlling mechanism that controls the exposure. Larger the aperture, higher is the exposure level. External light is also a factor, but it is not controllable by the camera unless a flash light, or reflectors are used. ISO value is not a factor that measures exposure; it is rather a sensitivity adjustment of the camera.
If exposure of the camera goes too high, the picture gets overexposed, and details are washed from the picture. If the exposure is too low, the picture becomes underexposed thus making the picture dark. A fine adjustment for exposure is available by using the exposure compensation.
What is the difference between Exposure and Brightness?
• Exposure is the amount of light that is incident on the sensor in the process of taking the picture.
• Brightness is how bright an object appears in the picture.
• Exposure is a property of the camera and the settings; brightness is a product of exposure.