Perspective control is a procedure for composing or editing photographs to better conform with the commonly accepted distortions in constructed perspective. The control would:
- make all lines that are vertical in reality vertical in the image. This includes columns, vertical edges of walls and lampposts. This is a commonly accepted distortion in constructed perspective; perspective is based on the notion that more distant objects are represented as smaller on the page; however, even though the top of the cathedral tower is in reality further from the viewer than base of the tower (due to the vertical distance), constructed perspective considers only the horizontal distance and considers the top and bottom to be the same distance away;
- make all parallel lines (such as four horizontal edges of a cubic room) cross in one point.
Perspective projection distortion occurs in photographs when the film plane is not parallel to lines that are required to be parallel in the photo. A common case is when a photo is taken of a tall building from ground level by tilting the camera backwards: the building appears to fall away from the camera.
In the two images shown to the right, the first suffers from perspective distortion — in the second that distortion has been corrected.
The popularity of amateur photography has made distorted photos made with cheap cameras so familiar that many people do not immediately realise the distortion. This "distortion" is relative only to the accepted norm of constructed perspective (where vertical lines in reality do not converge in the constructed image), which in itself is distorted from a true perspective representation (where lines that are vertical in reality would begin to converge above and below the horizon as they become more distant from the viewer).
Read more about Perspective Control: Perspective Control At Exposure, Perspective Control in The Darkroom, Perspective Control During Digital Post-processing, Perspective Control in Virtual Environments, See Also
Famous quotes containing the words perspective and/or control:
“All things being equal, I would choose a woman over a man in order to even the balance of power, to insinuate a different perspective into the process, to give young women something to shoot for and someone to look up to. But all things are rarely equal.”
—Anna Quindlen (b. 1952)
“If someone does something we disapprove of, we regard him as bad if we believe we can deter him from persisting in his conduct, but we regard him as mad if we believe we cannot. In either case, the crucial issue is our control of the other: the more we lose control over him, and the more he assumes control over himself, the more, in case of conflict, we are likely to consider him mad rather than just bad.”
—Thomas Szasz (b. 1920)