Digital filtering is digital processing of images, sound or other spatial or time-series data which still leaves them in the same overall form (e.g. image to image), but where some aspects are enhanced, transformed or cleaned up. For example, applying smoothing out a sound track to remove clicks, or edge enhancement on an image. Some digital filtering emulates analogue filtering, especially for audio filtering. Digital filtering often uses simply linear processing of the data such as weighted sums or averages of neighboting items. Almost always digital filtering is local, applying to a pixel or sound sample and its close neighbours.
Examples of digtal filtering include a moving average for time series or a Gaussian filter for smoothing an image.
Defined on page 248
Used on page 248
Applying a digital filter to an image.
Gaussian filter with σ = 0.8