Vignetting

Usually described as the darkening of the edges of a photographic image due to the inability of a lens to evenly distribute light to the corners of the frame. It can be viewed as negative aspect of some lenses and ‘removed' in post processing. However, Vignetting is often valuable as a creative device to direct the eye back to the centre of the frame or to create a retro/vintage feel. It is also sometimes used to describe a darker centre and lighter edges/corners.