1. A computer-implemented method for detecting an object of interest, the method comprising: generating an edge image from an image of a scene; generating a sectioned structure comprising a plurality of sections for use in analyzing the edge image; analyzing the edge image using the sectioned structure, wherein analyzing the edge image comprises: identifying a plurality of edge pixel densities representing the number of edge pixels within each of the plurality of sections of the sectioned structure at each of a plurality of pixel locations in the edge image; comparing the plurality of edge pixel densities identified to a plurality of reference densities for a reference image to generate the plurality of variances for the plurality of pixel locations; and detecting a presence of the object of interest in the edge image when at least one pixel location in the plurality of pixel locations has a variance in the plurality of variances that is below a selected threshold.