The invention relates to a white opaque film formed from a crystallizable thermoplastic, preferably thermo-plastic polyester in the form of polyethylene terephthalate, barium sulfate and titanium dioxide as pigments, at least one optical brightener, and optionally at least one dye soluble in the thermoplastic. The film optionally includes, an additional functionality, e.g. in the form of an adhesive coating, of a coating with aminosilane or silicone, of UV resistance, of hydrolysis resistance, of flame retardancy, or of a sealable outer layer.