Anamorphic projection

Anamorphosis is a distorted projection or perspective requiring the viewer to use special devices or occupy a specific vantage point (or both) to reconstitute the image. The word "anamorphosis" is derived from the Greek prefix ana‑, meaning "back" or "again", and the word morphe, meaning "shape" or "form". An optical anamorphism is the visualization of a mathematical operation called an affine transformation. The process of extreme anamorphosis has been used by artists to disguise caricatures, erotic and scatological scenes, and other furtive images from a casual viewer, while revealing an undistorted image to the knowledgable spectator.

There are two main types of anamorphosis: perspective (oblique) and mirror (catoptric). More-complex anamorphoses can be devised using distorted lenses, mirrors, or other optical transformations.

Examples of perspectival anamorphosis date to the early Renaissance (fifteenth century). Examples of mirror anamorphosis were first seen in the late Renaissance (sixteenth century).

With mirror anamorphosis, a conical or cylindrical mirror is placed on the drawing or painting to transform a flat distorted image into an apparently undistorted picture that can be viewed from many angles. The deformed image is painted on a plane surface surrounding the mirror. By looking into the mirror, a viewer can see the image undeformed.

Leonardo's Eye (Leonardo da Vinci, c. 1485) is the earliest known definitive example of perspective anamorphosis in modern times. The prehistoric cave paintings at Lascaux may also use this technique, because the oblique angles of the cave would otherwise result in distorted figures from a viewer's perspective.

Hans Holbein the Younger is well known for incorporating an oblique anamorphic transformation into his painting The Ambassadors. In this artwork, a distorted shape lies diagonally across the bottom of the frame. Viewing this from an acute angle transforms it into the plastic image of a human skull, a symbolic memento mori. During the seventeenth century, Baroque trompe l'oeil murals often used anamorphism to combine actual architectural elements with illusory painted elements. When a visitor views the art work from a specific location, the architecture blends with the decorative painting. The dome and vault of the Church of St. Ignazio in Rome, painted by Andrea Pozzo, represented the pinnacle of illusion. Due to neighboring monks complaining about blocked light, Pozzo was commissioned to paint the ceiling to look like the inside of a dome, instead of building a real dome. As the ceiling is flat, there is only one spot where the illusion is perfect and a dome looks undistorted.

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