Backlight compensation
While a camera's automatic exposure control tries to get the lightness of an image to appear as the human eye would see a scene, it can be easily fooled. Think of the case where a person walks into a fairly dark room with a flashlight in her hand and directs this flashlight to the camera. Although the light source is quite small, it makes the camera believe the scene has become brighter and the camera's exposure control automatically adjusts to it, resulting in a darker image. To avoid this, a mechanism called backlight compensation is introduced. It strives to ignore small areas of high illumination, just as if they were not present at all. With backlight compensation, the image from the example above would have the same exposure regardless of whether the flashlight was present or not. The resulting image enables the person to be visually seen and identified. Without backlight compensation, the image would be too dark, and identification would be impossible.