An apparatus and method for enhancing the quality of a digital video
signal uses coding information for use in connection with spatial domain
sharpness enhancement algorithms used in multimedia devices. The
sharpness of previously encoded or transcoded digital video images is
enhanced without enhancing encoding artifacts. The apparatus includes a
usefulness metric generator that identifies a limit to the sharpness
enhancement of an image that can be applied to a previously coded digital
video that represents a sequence of images without enhancing coding
artifacts. The usefulness metric generator applies the usefulness metric
to at least one sharpness enhancement algorithm. The usefulness metric
and the sharpness enhancement algorithm are separate so that the
usefulness metric can be used with a variety of video enhancement
algorithms.