filtering - technical definition

Also known as image decimation. In video compression, a step that reduces the total frequency of the analog signal through a process of averaging the values of neighboring pixels or lines. For example, adjoining black and white pixels become gray pixels.Taps are the number of lines or pixels considered in this process. MPEG, for example, uses a seven-tap filter. See also analog, compression, frequency, MPEG, pixel, signal, and video.