Development of a spectral imaging system based on a liquid crystal tunable filter

dc.contributor.author	Evans, MD	en
dc.contributor.author	Thai, CN	en
dc.contributor.author	Grant, JC	en
dc.date.accessioned	2014-06-06T06:43:28Z
dc.date.available	2014-06-06T06:43:28Z
dc.date.issued	1998	en
dc.identifier.issn	00012351	en
dc.identifier.uri	http://62.217.125.90/xmlui/handle/123456789/1293
dc.relation.uri	http://www.scopus.com/inward/record.url?eid=2-s2.0-0032214887&partnerID=40&md5=2b3781f4d0fa8590b556f79d59b910d6	en
dc.subject	Bean	en
dc.subject	Filter	en
dc.subject	Imaging	en
dc.subject	Liquid crystal	en
dc.subject	NDVI	en
dc.subject	Nitrogen	en
dc.subject	Plant health	en
dc.subject	Spectra	en
dc.subject.other	Liquid crystal filters	en
dc.subject.other	Normalized difference vegetation index (NDVI)	en
dc.subject.other	Attenuation	en
dc.subject.other	Computer control systems	en
dc.subject.other	Computer software	en
dc.subject.other	Crops	en
dc.subject.other	Electric filters	en
dc.subject.other	Gain control	en
dc.subject.other	Imaging systems	en
dc.subject.other	Light transmission	en
dc.subject.other	Liquid crystals	en
dc.subject.other	Nitrogen fertilizers	en
dc.subject.other	Vegetation	en
dc.subject.other	Video signal processing	en
dc.subject.other	Remote sensing	en
dc.subject.other	Phaseolus (angiosperm)	en
dc.title	Development of a spectral imaging system based on a liquid crystal tunable filter	en
heal.type	journalArticle	en
heal.publicationDate	1998	en
heal.abstract	This article presents an approach to the integration of a liquid crystal tunable filter into a monochrome video imaging system and provides a scheme for leveling the system response across wavelengths in the face of varying illumination, filter transmittance, camera lens aperture settings, and gain response. The scheme developed here uses the filter attenuation control and the camera gain control, both of which can be controlled via software. This system was applied to the evaluation of vigor of bush bean plants grown under different nitrogen treatments (from 30 to 120 ppm N). Using plant images captured at 695 nm and 760 nm, a Normalized Difference Vegetation Index (NDVI) was computed for each plant canopy and showed a increasing trend with increasing nitrogen treatments.This article presents an approach to the integration of a liquid crystal tunable filter into a monochrome video imaging system and provides a scheme for leveling the system response across wavelengths in the face of varying illumination, filter transmittance, camera lens aperture settings, and gain response. The scheme developed here uses the filter attenuation control and the camera gain control, both of which can be controlled via software. This system was applied to the evaluation of vigor of bush bean plants grown under different nitrogen treatments (from 30 to 120 ppm N). Using plant images captured at 695 nm and 760 nm, a Normalized Difference Vegetation Index (NDVI) was computed for each plant canopy and showed a increasing trend with increasing nitrogen treatments.	en
heal.journalName	Transactions of the American Society of Agricultural Engineers	en
dc.identifier.issue	6	en
dc.identifier.volume	41	en
dc.identifier.spage	1845	en
dc.identifier.epage	1852	en