1. An object detection system, the system comprising: a far IR sensor operable to sense thermal radiation of objects and surroundings in a field of view and to generate a far IR image in response thereto; and an image processing device operable to receive and process the far IR image, the image processing device is-configured to: process the far IR image by generating an initial threshold image based on the far IR image and an initial threshold value; iteratively obtain a number of successive threshold images based on the far IR image and a number of successively increased threshold values, each increase resulting in an image whose pixels represent objects having higher temperatures; and obtain a number of largest component threshold images based on the number of successive threshold images and the number of successively increased threshold values; for each of the number of successively increased threshold values, calculate a centroid angle within the field of view from the number of largest component threshold images to obtain a number of centroid angle values; calculate a plurality of centroid values based on the number of centroid angle values and the number of successively increased threshold values; calculate a plurality of distances between the plurality of centroid values; determine a centroid convergence condition as defined by the plurality of distances between the plurality of centroid values, wherein a plurality of distances below a common distance value for successive centroid values signal a convergence by approaching and maintaining a relatively consistent distance as the threshold approaches a maximum; and determine the presence or absence of an object in the field of view based on the initial threshold image, the number of successive threshold images, the initial threshold value, the successive threshold values, and the centroid convergence condition.