Superimposed

Superimposed refers to something that has been placed or layered on top of something else, so that the two are visible together. The term comes from the Latin superimponere, meaning to place over. In common use, it often describes images, features, or data that are laid over a background to form a composite.

In imaging and visual media, superimposition is a technique for combining two or more images. Earlier photographers used methods such as double exposure or optical printing to overlay scenes; in modern workflows, digital editing software allows precise control over transparency, alignment, and masking to create complex composites. Superimposed elements are also used in design and art to convey layered meaning or context.

In science and engineering, superposition has a more formal meaning. The superposition principle states that, for linear systems, the overall response is the sum of the responses to individual inputs. This idea underpins the use of superimposed waveforms in physics and electrical engineering, and it informs methods for analyzing structures by adding the effects of separate loads or forces. A related concept is the superimposed load in structural engineering—the idea that loads applied after construction, such as occupancy or furnishings, can be treated as additional forces on a building.

In geographic information systems and cartography, map layers are frequently superimposed to create a richer representation of data, such as roads over imagery or zoning over topography. In medical imaging, projection artifacts can cause anatomical structures to appear superimposed, sometimes complicating interpretation.