lines of various width, representing a specific amount of exposure within a certain range. This led to the use of the Sabattier effect in the fields of Photogrammetry and Equidensitometry. Agfacontour Professional Film In 1970, Agfa marketed Agfacontour Professional Film, which simplified the process of obtaining consistent results for images that looked similar to pseudo-solarized images and therefore it was widely used in equidensitometry and art. This special purpose film addressed the uncertainty of pseudo-solarisation results. As of 2002, Agfacontour Film was no longer being produced. In digital media Early video synthesiser technologists concerned themselves with achieving arbitrary curves not limited by film chemistry. A goal was to extend the range of pseudo-solarization effects possible to a computer specified curve. They then applied the defined solarization curve to real time video images. A video lookup table was often used to implement this. 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. This was an especial advantage for creating colour solarizations with 3 primary colours. Graphs describing pseudo-solarization curves typically place input range of tones on the x axis, with black at 0 and white to the right, and the output range of tones on the y axis with black at 0 and white up. A curve then defines the input to output mapping. Manipulating custom curves in photo-editing programs such as Photoshop provide tools to mimic the Sabattier effect in digital image processing. References Langford, Michael. The Darkroom Handbook. New York: Dorling Kindersley Limited, 1981. p. 236–243. External links Unblinking Eye - Controlling the Sabatier Effect Photographic techniques Science of photography Photographic techniques dating from the 19th century