1. A system for generating a digital subtraction image of at least two input images, comprising a registration subsystem ( 1 ) for generating a plurality of different registrations of the input images ( 7 , 8 ), based on different values of a registration parameter ( 6 ); a subtraction subsystem ( 2 ) for generating a plurality of subtracted images by subtracting the input images in accordance with respective ones of the plurality of registrations; a combining subsystem ( 3 ) for combining the plurality of subtracted images into a combined subtracted image ( 9 ).