It separates the wavelengths using passive optical components such as bandpass filters and prisms. Thus they can act as narrow bandpass filters. Generally, washable true HEPA filters are expensive. Fitting Diesel Pre Filters in exhaust system. Liquid crystal light valves work by rotating light between two polarizing filters. Other passband filters are also used. These filters were specified as particular combinations of glass filters and photomultiplier tubes. The most common color filters used are red and cyan. Two multistage "cyclone" air filters were used to improve dust removal. Digital filters can be used in the design of finite impulse response filters. Color images are created by combining separate monochrome images taken through different filters. However, on earth, air filters the incoming light, changing the solar spectrum. It is primarily used in conjunction with pipes and filters. LEDs are highly efficient at producing colored light compared with incandescent lamps and filters. The plugin system allowed for addition of new file formats and new effect filters.