Dictionary

underfilter en · NOUN

Pronunciation

• (US) audio

Etymology

From under- + filter.

Meanings

1. A morphological filter (idempotent operator) whose image is a subset of the domain.
   • It is clear that overfilters and underfilters are dual in the sense of the duality principle. 1999, Edward R. Dougherty, Jaakko Astola, Nonlinear Filters for Image Processing, page 180:
2. A filter that is positioned beneath something.
   • A single sheet of filter paper is used as an underfilter. 1992, Margaret M. Manson, Immunochemical Protocols, page 445:
   • In addition, the flow from the underfilter, which had previously been clear, became cloudy, indicating that the filter had failed to block particles from the core. 2004, R.F. Craig, Craig's Soil Mechanics, →ISBN, page 430:
   • The paving downstream consisted of 18x18x8-inch blocks laid on edge over a brick base which in turn was underlain with a gravel or brick chip filter. Since there was some controversy as to whether an underfilter was necessary, the first test was made with the filter omited.^([sic]) 1967, Journal of the Institution of Engineers Pakistan:
   • Since there is no underfilter, the top flow line emerges on the downstream slope. 1988, Árpád Kézdi, László Rétháti, Handbook of Soil Mechanics, page 61:

Forms

Coordinates

overfilter

underfilter en · VERB

Pronunciation

• (US) audio

Etymology

From under- + filter.

Meanings

1. To filter insufficiently.
   • Underfiltering by using too high a cut-off frequency leaves too much noise in the reconstructed images (bottom row). 1994, Douglas Van Nostrand, Selected Atlases of Cardiovascular Nuclear Medicine, →ISBN, page 35:
   • You don't want to underfilter. Nor do you want to filter beyond what is economically justifiable. 1978, Hydraulics and Pneumatics:
   • It is not possible to overfilter your tank but marine aquaria are frequently underfiltered. 1966, William P. Braker, Know how to Keep Saltwater Fishes, page 19:

Forms