Sub-pixel area calculation methods for estimating irrigated areas - Thenkabail, Prasad S.; Biradar, Chandrashekhar M.; Noojipady, P.; Xueliang Cai; Dheeravath, Venkateswarlu; Li, Y.J.; Velpuri, Naga Manohar; Gumma, Murali K.; Pandey, Suraj (2007)