1. A method for use in extraction of foreground objects in an image stream, the method comprising: providing input image data of a region of interest; providing a background model of said region of interest; providing data indicative of pixel to meter ratios in said input image data; and utilizing said background model and processing each image in said input image data, wherein said processing comprising: determining a background gradient map for pixels in said background model and an image gradient map for pixels in the image; determining one or more distance segments in said input image data using said data indicative of pixel to meter ratios and defining a predetermined number of one or more segments in said image and corresponding one or more segments in the background model such that pixels of said one or more segments correspond to one of said one or more distance segments; and for each image segment, determining an edge density factor being a first relation between the image and background gradient maps for said segment, and calculating a foreground detection threshold based on said certain relation, thereby enabling use of said foreground detection threshold for classifying each pixel in the segment as being a foreground or background pixel.