In the majority of cases, the colored or graphic film is thermoformed and then set into the tool for injection molding of the thermoplastic or thermoset behind it, though in several lower pressure processes it can be vacuum formed into a hot tool and then thermoset plastic injected in second step into the closed tool. The film's advantages are in reducing painting process costs, providing durable and unique graphics, and also effectiveness in blocking visibility (read-through) of glass fibers when injection molding long-fiber-reinforced thermoplastics, and glass-reinforced thermosets, like polyurethanes.
For reference and illustration examples, please see links here:
http://www.fusionuv.com/Film_Insert_Molding_Used_in_Automotive_Component_Decoration.aspx (illustration above)
I hope you find this helpful in furthering awareness on where this process can amp up the quality and 'knarliness' of a design area.