Lighting is the very essence of filmmaking. The way that a scene is lit can create an emotional response in the viewer every bit as profound as the music that accompanies it. Lighting can help define characters, and defines an entire genre in the case of film noir. Professional lighting techniques in the art of the cinematic film range from very subtle to ostentatious.
Hard lighting refers to lighting in which the shadows are very clearly defined. Shadows are an integral part of film noir, as the physical presence of shadows underlines the psychological uncertainly of characters who combine good and evil to become shadowy figures in the emotional geography of the film.
Soft lighting has more nuance and creates far more diffuse illumination. Soft lighting can also soften the hardness of certain characters to stimulate a positive emotional response to them in the audience.
Frontal lighting attempts to extinguish all shadows. The result is a rather flat image that loses dimension. This can give the scene a poster-like unreal effect.
Side lighting does the opposite of frontal lighting in that it seeks angularity rather than flatness. Side lighting is very effective at producing emotional resonance in a character by highlighting noses, cheekbones and lips. This effect is usually accompanied by hard shadows cast to the other side of the actor.
Backlighting attempts to provide a greater feeling of depth by making the object of the film stand out against a diffuse background. This lighting technique can create feelings of the locale overwhelming the character. Backlighting also helps to create a sense of dislocation and disorientation in the character or scene.
Underlighting is light that comes from below the subject. Underlighting is used quite effectively to produce scenes of horror because it can produce a grotesque effect on the features of a face.
Key lighting has no side lighting to diffuse the shadows and so a face can appear as a slash of white in the darkness surrounding it. The key light provides exacting illumination of the subject and is sometimes accompanied by fill lighting.
Fill lighting is used to soften the shadows produce by key lighting. When fill lighting is used with backlighting, it can produce a striking image of a dark character within a dark setting.
Silhouette lighting creates dark, strongly outlined silhouettes against a bright background. This is an effective technique for introducing unknown characters to the audience.