Abstract: A remapping apparatus and method dynamically map the endpoints of a manual control to scaled and shifted values of a controlled parameter magnitude, such that the full span of the control corresponds to transition of a controlled parameter between desired endpoints, normally over less than the full possible span of transition. The mapping is recalculated repetitively and accounts for constraints on the controlled parameter resulting from variations in related parameters. The apparatus and method are especially applicable to controlling transition effects produced by a video switcher. A digital computer senses the position of the control and registers the level of a controlled parameter (and preferably also the level of constraining related parameters).