Ambient Lighting
From Swikipedia
Introduction
Ambient light, also called available or existing light, refers to the illumination surrounding a subject or scene, specifically any and all light not provided by a photographer. It is a term commonly used by photographers, cinematographers and other practitioners of the visual arts.
Levels of ambient light are most frequently considered relative to additional lighting used as fill light, in which case the ambient light is normally treated as the key light. In some cases, ambient light may be used as a fill, in which case additional lighting provides the stronger light source, for example in bounce flash photography. The relative intensity of ambient light and fill light is known as the lighting ratio, an important factor in calculating contrast in the finished image.
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