1. A non-transitory computer-readable storage medium having instructions embodied thereon, the instructions being executable on a processing apparatus to detect an object in an image by at least: producing a high-pass filtered version of the image, the high-pass filtered version comprising a plurality of pixels; for at least some of the plurality of pixels, determining a deviation parameter between the value of a given pixel and a reference value; and based on the deviation parameter meeting a criterion, providing an indication of the object being present in the image.