the fill light, a secondary light source of slightly less intensity than the key light which is placed at eye level.
Yet even this combination of key and fill light is must be supplemented further if a director is seeking to create a sense of depth. The third light source that provides the necessary depth is known as the back light, as it is placed above and behind the subject. Used on its own, the back light alone would create a silhouette of the subject. But the triple combination of key, fill and back lights, separates the subject from its environment and creates a feeling of depth.
Lighting techniques can be divided into high key or low key categories. A low contrast ratio of key and fill light will result in an image of almost uniform brightness. This is termed high key lighting. This is a standard, conventional lighting scheme employed in Bollywood musical