In photography and optics, vignetting (pron.: //; French:
"vignette") is a reduction of an image's brightness or
saturation at the periphery compared to the image center. The
word vignette, from the same root as vine, originally referred
to a decorative border in a book. Later, the word came to be
used for a photographic portrait which is clear in the center,
and fades off at the edges. A similar effect occurs when filming
projected images or movies off a projection screen. The
resulting so-called "hotspot" effect defines a cheap home-movie
look where no proper telecine is used. Vignetting is often an
unintended and undesired effect caused by camera settings or
lens limitations. However, it is sometimes purposely introduced
for creative effect, such as to draw attention to the center of
the frame. A photographer may deliberately choose a lens which
is known to produce vignetting to obtain the effect, or it may
be introduced with the use of special filters or post-processing
procedures. There are several cause