Loretta lux photoshop technique

The Sabatier effect which is also referred to as soloarisation , is a traditional process of exposing a print to white light for a secong time during its development.

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This in turn reverses the tonal curve on certain parts of the image. The result; an image that is part positive and part negative. 
It was somewhat perfected by Armand Sabatier but the the phenomenon was first documented by a H. de la Blanchere in 1859 in L’Art du Photographe. Having said this, solarisation was already known by Daguerre and is known to be one of the earliest effects in photography.

Throughout the years, this technique has been perfected by a number of well known traditional photographers such as Hershel and more recently by Man Rays assistant Lee Miller where she accidentally discovered this technique.

There are many who claim to have 'discovered' this technique throughout the years.

Solarised Portrait of Meret Oppenheim, Paris, 1930

Solarisation is most effective when About - Loretta Lux VIQA