An apparatus for forming transitioned edges in patterns formed by a scanning laser in a dyed textile material is disclosed. The transition rate between the untreated material and the treated material is controlled by passing a scanning laser beam(21) through a mask(50) prior to the laser beam(21) reaching a focal point. An apertured mask(50) can be employed to control the transition rate, wherein the location of the aperture(51) relative to the focal point of the laser beam(21) and configuration of the aperture periphery are manipulated to effect the transition rate.