K Key 148 This is used to describe the overall tone of a photograph ­ more commonly for black-and-white portraiture although it can equally well relate to colour imagery. The key light or main light sets the character or the mood of an image. High-key refers to an image that is predominantly composed of lighter tones while low- key refers to an image composed largely of darker tones. This is not the same as under- and overexposure as both high- and low-key images still have a full tonal range. Pictured: flower photography in high-key and low-key style showing tonal bias. High-key image Low-key image see Exposure 108, Tone 251