Every camera lens is bound to have a level of error in it. This leads to luminance drops and patterns such as lens flares, glares, and chromatic aberrations. Some lenses are used to capture images with distorted or enhanced perspectives, such as the fish eye lens and spherical lens. Adding these effects to a CG image will enhance the realism of it. Blender provides a very wide range of nodes to achieve these distortions.
Glare is a discomfort of vision in the presence of a bright source of light. This is seen in any photograph with a light source in its content. This phenomenon exhibits streaks, discs, or foggy rays shooting away from the source. Adding these effects adds realism to the image.
Blender's Glare node provides multiple options to simulate this behavior. The following screenshot illustrates the four types of glares available in Blender's Glare node:
