While editing your pictures in a software or in a photo editor, you must have come across certain adjustments to set the correct light in your picture. Or if a picture came out with the wrong or unwanted lighting, what do you use between brightness and exposure?
While it may seem that both of them do the same work of “brightening” or “darkening” the picture, they both work on different fundamentals and if you observe closely they affect a picture in different manners. So then what exactly is the difference between brightness and exposure?
How do brightness and exposure work?
Brightness is simply how dark or light a picture is. Correct brightness is important to easily understand the contents of the picture. It is the simplest of the tools present in photo editors for light adjustment. Changing the brightness of a picture affects all pixels equally. Increasing it will make the dark areas lighter and light areas lighter too. Similarly, decreasing the brightness will make light areas darker and the dark areas darker too. Changing the brightness can help improve the visibility of the darker parts of the image.
Exposure is something entirely different. It is an in-camera property of a picture. When clicking a picture, exposure is the amount of light that enters the lens of the camera. In other words, how exposed is the lens to the light entering the camera. Exposure can be controlled by changing the camera settings beforehand. When less than the required light enters the camera, the picture is said to be under-exposed. When more than the required light enters the camera, the picture is said to be over-exposed.
Exposure can be adjusted during the processing stage. Unlike brightness, exposure is highly biased towards the highlights in the picture. In layman language, it will act as if increasing the amount of light in the picture, without much affecting the darker areas in the picture.
Difference between the two
The difference between brightness and exposure is that when you have a picture which has a lot of highlights and you want to brighten the image, you do not use exposure, since it specially affects highlights. You should use brightness in this case so the whole picture is affected. And if you want to pull back the highlights, then use exposure and not brightness since it will darken the whole image.
Hence analysing your picture for highlights and shadows will give you a fair idea of whether to use brightness or exposure while adjusting the light.