High key lighting aims to reduce lighting ratios and shadows for a more even, homogeneous light. It creates low contrast between brighter and darker areas. High key lighting was commonly used in classical Hollywood films and sitcoms due to its suitability for three-point lighting setups.
Low key lighting uses predominantly shadowy areas lit by a single key light and minimal fill. It heightens a sense of alienation in the viewer and is often used in film noir and horror genres. Romantic dramas conventionally use high key lighting for joyous scenes and low key lighting for sorrowful scenes to depict emotions. The director challenged these conventions by using high key lighting for crying scenes in the romantic drama "Melancholia".