Glare is called a certain course (state) of the visual process in which there is a sensation of discomfort or a reduction in the ability to recognize objects, or both, as a result of the inappropriate distribution of luminance or an inappropriate range of luminance or excessive contrasts in space or time.
From the point of view of the existing effects, the following types of glare are distinguished:
- Disturbing - reducing the ability to see for a very short but noticeable time and without causing a feeling of unpleasantness. The excessive amount of light reaching the eye is scattered in the optical centers of the eye, which causes the overlap of the so-called haze luminance into a correctly focused image of the observed object. An example of this type of glare can be the situation when, after a short-term observation of the filament of the bulb, we would try to thread the needle with a thread. Perception of the so-called "scotomas" (it is the luminance of haze that superimposes the observed image) for a short but noticeable period prevents this activity;
- Unpleasant - causing a feeling of unpleasantness, discomfort, irritation and affecting the lack of concentration without reducing the ability to see. As soon as the cause of the glare is removed, the discomfort subsides. This glare depends on: the luminance of individual dazzling sources, the luminance of the background on which the sources are located, the angular values of these sources, their position relative to the observer and their number in the field of view. An example of this type of glare can be the observation of an open space evenly covered with pure snow on a sunny day. In every direction of observation, the whiteness of the snow seems to dazzle the eyes and cause a feeling of discomfort;
- Blinding - a glare so strong that no object can be seen for a certain period of time. It is an extreme case of disturbing glare. An example of this type of glare can be a situation when, while staying at night on an unlit road, a car coming from the opposite direction with the road lights on, suddenly appears in the field of view. Glare loses the ability to perceive for a short but noticeable period of time.
We wrote about how to reduce glare here