underfilter
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English[edit]
Etymology[edit]
Noun[edit]
underfilter (plural underfilters)
- (signal processing) A morphological filter (idempotent operator) whose image is a subset of the domain.
- 1999, Edward R. Dougherty, Jaakko Astola, Nonlinear Filters for Image Processing, page 180:
- It is clear that overfilters and underfilters are dual in the sense of the duality principle.
- A filter that is positioned beneath something.
- 1967, Journal of the Institution of Engineers Pakistan:
- 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]
- 1988, Árpád Kézdi, László Rétháti, Handbook of Soil Mechanics, page 61:
- Since there is no underfilter, the top flow line emerges on the downstream slope.
- 1992, Margaret M. Manson, Immunochemical Protocols, page 445:
- A single sheet of filter paper is used as an underfilter.
- 2004, R.F. Craig, Craig's Soil Mechanics, →ISBN, page 430:
- 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.
Coordinate terms[edit]
Verb[edit]
underfilter (third-person singular simple present underfilters, present participle underfiltering, simple past and past participle underfiltered)
- To filter insufficiently.
- 1966, William P. Braker, Know how to Keep Saltwater Fishes, page 19:
- It is not possible to overfilter your tank but marine aquaria are frequently underfiltered.
- 1978, Hydraulics and Pneumatics:
- You don't want to underfilter. Nor do you want to filter beyond what is economically justifiable.
- 1994, Douglas Van Nostrand, Selected Atlases of Cardiovascular Nuclear Medicine, →ISBN, page 35:
- Underfiltering by using too high a cut-off frequency leaves too much noise in the reconstructed images (bottom row).