1. A method of increasing the contrast between an object and space when photographing a transparent object, the method comprising: with a radiation source, illuminating a transparent object with radiation in a region of the spectrum having wavelengths to which the transparent object is impermeable; filtering said radiation before impinging on said transparent object to block radiation having wavelengths to which said transparent object is permeable and to pass radiation having wavelengths to which said transparent object is impermeable; and, with a camera, photographing said object from the side of the object opposite the radiation source thereby obtaining a contour image of said object, said camera being capable of detecting radiation in the wavelength region being transmitted from the filtering step.