### device:

Filter
* Many filters require periodic cleaning to remove trapped matter and organisms
  - use color transformation, or affect the colors in the image in other ways
* Remove any foreign matter usually found in gases such as oil and sludge.
* Some filters combine a larger pore size with resin which releases iodine on demand
  - mechanical and chemical methods to reduce impurities
* are CDMs that communicate with the storage device
  - commands that change files
  - commonly of fabric, fiber, ceramic or other screening material
  - devices
  - effective in removing all organisms except the smallest viruses
  - electrical devices
  - intermediate objects between the source and destination of a flow
  - mechanical devises unable to think or make judgements
  - part of cigarettes
  - programs that are often command-line oriented
  - reactive objects that monitor and classify event flow within a distributed system
  - sets of instructions that determine how e-mail programs deliver specific messages
  - tools that block Internet content
* are used for filtrates
  - purifying water
* are used to enhance contrast
  - take away parts of the signal
  - view an object at particular frequencies or frequency ranges
* block all but the fluorescent wavelengths of light emitted by the suspended cells
  - ultraviolet radiation from sunlight and artificial light
* can take out some chemicals from drinking water.
* collect dirt and dust and, in some cases, even contribute to indoor air pollution.
* come in two main shapes, round and square.
* control the wavelengths of light recorded.
* create electronic noise, the deeper the filter, the greater the noise.
* differ greatly in their ability to disinfect water.
* help keep ventilation systems free of dust and dirt.
* humanize the mathematical hard edges of images.
* operate by absorption or interference.
* pass some light and absorb others.
* polypropylene membrane manufactured without glue, adhesives, metal, or epoxy.
* produce color by subtracting wavelengths of light.
* remove dust and insects.
* uses in making color separations, red, blue, green.
* work by physically trapping particles larger than the pore size
  - rejecting light in certain frequency ranges
+ Filter (internet), Where filters are used
  * Filters are very common in e-mail systems. Online games, usually children's games, sometimes have filters. Wikis have filters, too.
+ Photographic filter: Photography
  * Filters can be cheap or expensive. Also some filters can be screwed in front of a lens, others can be placed in the back of the lens, or in special filter holders screwed in at the front.
+ Synthesizer, How synthesizers work: Electronic musical instruments :: Audio technology
  * The signal can then be sent to one or more filters. Filters are used to take away parts of the signal.

### device | filter:

Air cleaner
* Most air cleaners provide only two or three fan speed settings
  - remove only particulate pollutants suspended in air
* Some air cleaners can remove inhalable particulates
  - create ozone, which is meant to break down gases and odors
* are most useful with smokers in the home.
* can be mechanical or electric.
* keep dust out of the cylinders, and that cuts down the carbon quite a bit.
* remove smoke.
* use electrical attraction, filters or ozone.