Fixer image, also Hidden face, is an ambiguous “fool image” in the form of a drawing or a painting where the motif is apparently unambiguous, but contains other figures and elements that the artist has hidden in the image and that the viewer often has to look for. The elements are inserted so that they follow lines and details in the main subject and become visible when the viewer focuses on them or looks at the image from a different point of view.

People often see hidden faces in things. Depending on the circumstances, this is referred to as pareidolia, the perception or recognition of a specific pattern or form in something essentially different. It is thus also a kind of optical illusion. When an artist notices that two different things have a similar appearance, and draws or paints a picture making this similarity evident he/she makes images with double meanings. Many of these images are hidden faces or hidden skulls.

These illusionistic pictures present the viewer with a mental choice of two interpretations: head or landscape, head or objects, head or architecture, etc. Both of them are valid, but the viewer sees only one of them and very often he/she cannot see both interpretations simultaneously.

History
In the late Middle Ages, picture puzzles, similar to so-called song puzzles, were a way for draftsmen to point out a grievance or to depict a satirical exaggeration in drawings without immediately having to fear punishment. In this sense, however, the picture puzzles also often served for amusement, in that one could perceive a different meaning of the drawn by turning, etc. Franz Kafka is quoted from his diary entry from 1911: “’What is hidden in a picture puzzle’ is ‘clear and invisible’: clear for those who have found what they were asked to look at; invisible to those who do not even know that there is something to be looked for. ” In other languages (English, French) becomesPicture puzzle simply equated with a puzzle or search picture.

Types
An apparently correctly constructed image, the object of which turns out to be impossible, such as B. the Penrose triangle. Such objects are called impossible figures.
The anchor in Esbjerg’s coat of arms is a search image that contains a figure that cannot be recognized at first glance.
An image that, thanks to its special construction, conveys different image content from different angles.
Anamorphosis is a special form of the picture puzzle.
Chance images.There are everyday examples of hidden faces, they are “chance images” including faces in the clouds, figures of the Rorschach Test and the Man in the Moon. Leonardo da Vinci wrote about them in his notebook: “If you look at walls that are stained or made of different kinds of stones you can think you see in them certain picturesque views of mountains, rivers, rocks, trees, plains, broad valleys, and hills of different shapes. You can also find in them battles and rapidly moving figures, strange faces and costumes, as well as an infinite number of things.” Francois and Jean Robert collected and published a lot of photos of “chance faces”.

Examples
In art history, there are many examples of hidden figures and faces in pictures. Not infrequently, the hidden motive is expressive of some message. For example, there may be skulls that are reminiscent of the transience of life (memento mori), but also comic or satirical comments in caricatures. Giuseppe Arcimboldo (1527–1593) is known for many imaginative still lifes where arranged objects form anthropomorphic (human-like) portraits. The form grip is also partly used in surrealism.

Fixing pictures are still most common as entertainment. Most often, there are “exploration pictures” as popular puzzle tasks for children with the urge to find hidden figures.

From optical illusions, ambiguous “alternating images” and “upside-down images” (in German called Kippfiguren and in English ambiguous images can be characterized as a kind of fixer images.

Hidden faces created by artists
The Mannerist master at the 16th-century imperial Habsburg courts of Vienna and Prague, Giuseppe Arcimboldo of Milan was probably the best known artist for creating extraordinary hidden faces. He arranged flowers, vegetables, fruits, shells, scallops and other animals, books and different things on the canvas in such a way that the whole collection of objects formed a portrait. His series of The Four Seasons seems to be the first use of this approach and technique. Arcimboldo’s composite heads were celebrated and imitated by his contemporaries but they were relatively forgotten until participants in the twentieth-century art movements rediscovered them, bringing them to the attention of art historians. He is considered as forerunner of Dada and Surrealism.

Some other famous Renaissance and Baroque artists created hidden faces:
Leonardo da Vinci
Albrecht Dürer
Tobias Stimmer
Hans Holbein the Younger
Matthäus Merian
Anna Maria Sibylla Merian
Marcus Gheeraerts the Elder
Wenzel Hollar
Josse de Momper

Salvador Dalí was fascinated by the technique of Arcimboldo and his paranoia-critical method was influenced by the Mannerist painter. For Dalí the Arcimboldo effect was a form of self concealment as well as this exhibitionist painter seemed, all throughout his life of constant posturing, to hide his real self behind the gaudy externals of his behaviour. Larvatus prodeo, “I wear a mask,” he could have said with Descartes and he used this quotation from the French philosopher for the epigraph of his novel Hidden Faces. Probably his most famous “hidden face” is Voltaire in his oil painting: “Slave Market with the Disappearing Bust of Voltaire”. Other Surrealist painters rediscovered the technique of hidden faces in the first part of 20th century:
Max Ernst
René Magritte

Istvan Orosz tries to combine the technique of anamorphosis with the hidden faces. Anamorphosis is used for those works of art that were made as distorted and unrecognizable through clever geometrical constructions. But when viewed from a certain point, or through a reflecting object placed upon it, the hidden image appears in its true shape, that is, it goes through retransformation. Orosz made experiments with anamorphoses not only in resurrecting the old technique but to improve and develop it. Instead of having a meaningless distorted image, his intent is to bring sense to the basic anamorphic picture, giving it meaning in itself with its second reading being revealed by viewing it from a different viewpoint such as looking at it through a special mirror. The ambiguous layers coming up by this approach make use of the connection or contrast of the two images within the same picture being independent from each other.

There are many other contemporary works using hidden faces:
Shigeo Fukuda
Octavio Ocampo
Sandro del Prete