Conditions for enhancing image contrast by the digital subtraction of X-ray projections registered at different spectrum distributions in the energy range of 5–25 keV are considered. An experimental scheme for recording digital projections based on a 1300 × 1030 detecting array with a pixel size of 6.7 μm is described. It is shown that, when an object is irradiated by polychromatic radiation, the use of a Ni filter and a NiCl2 contrast solution provides results that were previously obtained by subtracting images on monochromatic spectral lines near the K jump in the absorption of the contrast substance. Schemes for recording color X-ray images in a dynamic mode using semitransparent X-ray monochromators are proposed.