What is vignetting in imaging systems?

Vignetting refers to the gradual decrease in brightness or saturation of an image as you move away from the center towards the edges. This phenomenon can occur in various imaging systems, including cameras and fluoroscopy setups. As the viewer or the imaging sensor captures light, the corners and edges of the frame may receive less light than the center, resulting in a noticeable drop in brightness towards these areas.

Understanding vignetting is essential for imaging professionals because it affects image quality, potentially obscuring critical details in the peripheral regions of an image where diagnostic information may be crucial. Recognizing and mitigating vignetting is an important aspect of optimizing imaging techniques in fluoroscopy and other modalities.

The other options describe different effects or issues unrelated to vignetting, such as distortion of lines or calibration errors, which do not relate to the brightness decrease characteristic of this particular phenomenon.