1. A method for analyzing captured images, the method comprising: capturing a first plurality of digital images of a field of view using a camera and at least one light source; identifying pixels of the first plurality of digital images that correspond to an object rather than to a background based on differences between first, second and third digital images captured by the capturing, the identifying including: forming a first difference image based upon a difference between the first digital image captured by the capturing and the second digital image captured by the capturing; forming a second difference image based upon the difference between the second digital image captured by the capturing and the third digital image captured by the capturing; and determining a third difference image, wherein each of one or more pixels of the third difference image comprises a pixel of a smaller pixel value between a corresponding pixel in the first difference image and a corresponding pixel in the second difference image, wherein the third difference image identifies the pixels that correspond to the object; and constructing a model of the object based on the identified pixels, the model including a position and a shape of the object.