A method and an arrangement for generating a composite video signal in accordance with the chroma-key method in which a virtual background spill signal is generated and added to the composite video signal to avoid darkening effects which are produced when eliminating spill light, and to eliminate brightening effects which are produced in "clean-up" operations. The background spill signal may consist of the product of a virtual spill signal source (SP) and a control signal (k.sub.3). The control signal (k.sub.3) is preferably the difference between a foreground control signal (k.sub.1) and a background control signal (k.sub.2), and both signals should be identical in the foreground and background ranges but different in spill ranges.