An image made by superimposing exposures of different subjects—most commonly as a double exposure.
Unwanted, accidental double exposures may occur in cameras which lack an interlock between film advance and the shutter release. Most post-1950s cameras offered double-exposure prevention; but some include an over-ride control when multiple exposures are deliberately sought.
Otherwise, film may be deliberately run through a camera twice, or the shutter cocked while holding down the rewind release button, to create double exposures. Alternatively, digital images may be layered in a software program to give the effect of a multiple exposure. Some digital cameras may offer this as a built-in effect, storing and merging the data from two exposures.