@article {780,
	title = {Camera to Emitter Distance Estimation Using Pixel Gray-Levels},
	journal = {Sensor Letters},
	volume = {7},
	year = {2009},
	month = {04/2009},
	pages = {133-142},
	publisher = {American Scientific Publishers},
	abstract = {In this paper, a camera to infrared emitter diode (IRED) distance estimation problem (CEDEP) is analysed, and a model for solving it is proposed. The model is based on image processing from a radiometric point of view. To define the model, the behaviour of accumulated image irradiance with different IRED radiant intensities, camera exposition times, and distances between the IRED and the camera were analysed. In the paper the model is defined and the calibration process used to obtain values for the model{\textquoteright}s parameters is described. Two experiments for distance estimation were carried out. The first experiment was over distances of 200 to 380 cm, where an error of less than 1\% was obtained. In the second experiment the CEDEP model was tested for distances of more than 400 cm. In the second experiment an error of 2\% was obtained over a range of distances between 400 and 600 cm. },
	issn = {1546-198X},
	doi = {10.1166/sl.2009.1023},
	author = {Jose L. Lazaro and Angel Cano and Oscar Esteban and Y. Pompa}
}
