X-ray radiation is transmitted through and scattered from an object under inspection to detect weapons, narcotics, explosives or other contraband. Relatively fast scintillators are employed for faster X-ray detection efficiency and significantly improved image resolution. Scatter and transmission images of the object are displayed, at least one being colorized in accordance with the effective atomic number of constituents of the object. Soft switching between photon-counting and photon integration modes reduces noise and significantly increases overall image quality.