Ringing artifacts are removed from a quantized image by an image
de-ringing filter that includes a determination unit, an adaptive filter
and a nonlinear low-pass filter. The determination unit determines
whether each selected pixel of a first set of selected pixels of an image
contains a ringing artifact based on, for example, gray-level values of
selected pixels within a determination kernel of pixels relating to the
selected pixel. The adaptive filter generates a filtered gray-level value
for each pixel determined by the determination unit to contain a ringing
artifact based on, for example, gray-level values of selected pixels
within a filtering kernel of pixels relating to the pixel. The nonlinear
low-pass filter generates a low-pass-filtered gray-level value for each
selected pixel of a second set of selected pixels of the image.