comb filter

comb filter

[′kōm ‚fil·tər]

(electronics)

A wave filter whose frequency spectrum consists of a number of equispaced elements resembling the teeth of a comb.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

comb filter

A bandpass filter used to process audio and video signals by mixing the original with a delayed signal. Comb filters allow selected frequencies to pass while blocking their harmonics and all other frequencies. Their most common application is to sharpen a composite video image by eliminating residual color (chroma) from the brightness (luma) signal that was not entirely filtered out in an earlier stage.

Early analog and two-line digital comb filters mix one line of video with the next. Since color signals are 180 degrees out of phase in alternating lines, the mixing removes most remaining color from the luma. A three-line digital comb filter averages the signal from the line before and after it to obtain a more accurate cancellation. The better a TV's comb filter, the less artifacts in the image (see dot crawl). See composite video.

Copyright © 1981-2025 by The Computer Language Company Inc. All Rights reserved. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction is strictly prohibited without permission from the publisher.