A graphics system for changing images on a gaming machine display, having a transition library of transition types, a graphics engine and a control means. The graphics engine applies a selected transition type from the transition library to at least one of at least two images for determining the way in which a substitution of one of the images by the other of the images occurs and initializes transition data for effecting an incremental substitution of the one image by the other image. The control means modifies the transition data such that, when the selected transition type is being effected, an incremental substitution of at least a part of the one image by the other image occurs serially until the one image has been substituted by the other image on the gaming machine display.