1. A computer-implemented method for analyzing a scene depicted in a sequence of video frames, the method comprising: receiving a raw video frame of the sequence of video frames; and for each of a plurality of pixels of the raw video frame, by operation of one or more computer processors: calculating a comparison measure between color-characteristics of a pixel in the raw video frame and color-characteristics of a corresponding pixel in a background image, wherein the comparison measure is defined in relation to a range of possible values of at least one color-characteristic of the pixel; upon determining the comparison measure of the pixel is within a specified threshold, classifying the pixel of the raw frame as depicting a portion of a background of the scene; and upon determining the comparison measure is outside the specified threshold, classifying the pixel of the raw frame as depicting a portion of a foreground of the scene.