Process and apparatus for producing a sheet or film exhibiting a colored band of varying color intensity, with an extruder for melting a stream of a thermoplastic synthetic resin and with a slot die tool (e.g. a fishtail die) having a distributor duct with a throttle zone arranged upstream thereof, a back pressure plate or restrictor bar, and a nozzle orifice, wherein a colorless melt stream and a dyed melt stream are respectively shaped into a sheet having the desired width and are melted together prior to exiting from the die tool along a lateral edge to form one sheet; and wherein along a predetermined width, calculated from a transition line of the dyed sheet, a wedge-like extending color band made up of a partial stream of the dyed melt stream is introduced into the zone of the colorless sheet by way of a slot die having a wedge-like orifice and being arranged in the extrusion direction upstream of the back pressure plate and downstream of the distributor duct, with a corresponding displacement of the colorless melt stream.