The digital center filter has clear advantages: As shading at the edge of the image is corrected after the image has been taken, the full brightness of the lens is retained while taking the photograph. Furthermore, there is no risk of light reflections, ghost images, or vignetting occurring if the light conditions or photographic location are not ideal, as is the case with analogue center filters.
For further information on this topic, please refer to the following website: http://www.digitalcenterfilter.com