Sabattier effect

Initially, the term "solarization" was used to describe the effect observed in cases of extreme overexposure of the photographic film or plate in the camera.

Seely,[8] separately, in successive issues of The American Journal of Photography, and in the same year by Count Schouwaloff in the French publication Cosmos.

It is evident from publications in the 19th century that this phenomenon was "discovered" many times by many photographers, as it tends to occur whenever a light is switched on inadvertently in the darkroom while a film or print is being developed.

In general the following facts are accepted by the community of photographic researchers:[12] Careful choice of the amount of light used and the precise moment in development to provide the additional exposure gives rise to different outcomes.

As a guide, an exposure of one second to a 25 watt incandescent lamp at two metres distance at around the end of the first minute of a 2-minute development can produce acceptable results.

Using the Sabattier effect it should be obvious that it is very difficult to manage all parameters for yielding consistent and predictable results and therefore other means have been pursued such as Agfacontour and special pseudo-solarizing developers[16][17] In scientific photography it was observed that when using photographic films with very high contrast (also known as lith films), the image produced by the Sabattier effect exhibited a multitude of lines of various width, representing a specific amount of exposure within a certain range.

[20] Early video synthesiser technologists concerned themselves with achieving arbitrary curves not limited by film chemistry.

Using this enhanced solarization technology, still photos could also be passed through a grey scale or colour lookup table with the advantage that the effect could be previewed and progressively improved, instead of a procedure based on darkroom exposure calculations applied on a one time basis to a volatile light sensitive film or print, as described above.

Manipulating custom curves in photo-editing programs such as Photoshop provide tools to mimic the Sabattier effect in digital image processing.