In more modern times, the use of graduated ND filters was popularized by Galen Rowell.
Neutral Milk Hotel | Electronic filter | Polarization density | Low-density polyethylene | High-density polyethylene | Digital filter | Cherry Filter | Air filter | Photographic filter | Ohne Filter | Nuclear density gauge | Neutral Nations Supervisory Commission | Neutral Nation | Neutral Bay, New South Wales | Neutral Bay | Low-density lipoprotein | Linear low-density polyethylene | Kalman filter | Idiom Neutral | High-density lipoprotein | digital filter | Water filter | water filter | The Neutral Ally | Spectral density estimation | Shiva amplifier chains showing spatial filter tubes (white) and Nd:glass amplifier structures (short blue tubes closest to camera). Portions of the 1982 Disney film ''Tron | Sand filter | Probabilistic data association filter | Oil filter | Neutral spine |