1. In a video signal processing system including a video signal processing channel, a kinescope for displaying images derived from processed video signals, and means for coupling processed video signals from said video channel to intensity control electrodes of said kinescope, apparatus comprising: a source of signals containing graphics information to be displayed by said kinescope; means coupled to said source of signals for deriving therefrom signals representative of graphics information to be displayed; bias means for providing a graphics intensity bias signal representative of a desired intensity level of displayed graphics information; first switching means having a signal input terminal coupled to said video channel, a signal output terminal coupled to said coupling means, and a switching control input terminal; second switching means having a signal input terminal coupled to said graphics bias signal, a signal output terminal coupled to said coupling means, and a switching control input terminal; and control means responsive to output signals from said deriving means for providing switching control signals to said switching control input terminals of said first and second switching means, for (a) enabling said first switching means to conduct video signals to said coupling means, and disabling said second switching means to prevent conduction of said graphics bias signal to said coupling means in a normal operating mode of said system when video signals alone are to be displayed, and (b) disabling said first switching means to prevent conduction of video signals to said coupling means, and enabling said second switching means to conduct said graphics bias signal to said coupling means during graphics display intervals in a graphics display operating mode of said system.