Grain grid method

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The grain grid method is a photographic method of color photography that works according to additive color mixing .

functionality

In the case of photographic films or plates that work according to the grain raster method, there are dye particles in front of the emulsion layer of a black and white film , which are colored in the three additive basic colors; In contrast to the line grid method , these particles are arranged irregularly and act like color filters during recording and projection .

Examples of grain raster films are:

The Autochromes also worked according to the grain grid method . The autochrome plate must not be confused with the autochrome process of printing technology .

History and Development

The basics of color photography go back to experiments by James Clerk Maxwell in 1861 , which were based on the theories about the physiological basis of color perception developed by Thomas Young at the beginning of the 19th century . The first practical applications for photography were developed by Louis Ducos du Hauron ( 1837 - 1920 ; raster process , 1875 ) and Charles Cros ( 1842 - 1888 ) and Frederic Ives ( 1888 ).

Early additive method of color photography have been developed with the color grid plate of James W. McDonough ( 1892 ), dyed in a glass plate with Farbpulverteilchen and then poured over an emulsion layer (first car Chrome plate), and the line scanning method of John Joly ( 1894 / 95 ; Joly method ).

However, the grain grid method did not establish itself until 1904 with the Autochromes by Auguste and Louis Lumière ; transparent starch grains with a grain diameter of 15 to 20 μm were obtained from raw and chopped potatoes, which were colored in equal volume proportions with the dyes blue, green and red and mixed after drying. This mixture was then applied with a density of about 7000 to 8000 potato starch grains per square millimeter of surface on a glass plate which was provided with a glue; A panchromatic emulsion was then poured onto this multiple filter layer. A colored slide was then obtained by reverse development . This process was first presented in Dresden in 1907 and used until around 1935 .

As early as 1908 , the Dornbirn doctor, musician and photographer Franz Bertolini ( 1875 - 1965 ) used the Lumière plates with the grain grid method; by 1925 he exposed hundreds of autochromes, around 600 of which have survived almost undamaged; a selection of these early color photographs by Bertolini were published in the volume Farben aus der Dunkelkammer (Haymon Verlag, 1996) edited by Hanno Platzgummer

1916 brought Agfa Autochrome- and grain grid plates as commercial product on the market; In industrial production, the starch granules were replaced by dextrin granules and resin particles as light filters.

See also

Further photographic processes after additive color mixing:

literature

  • Hanno Platzgummer (Ed.): Colors from the darkroom. Franz Bertolini's Autochrome, 1908–1925. Haymon, Innsbruck 1996, ISBN 3-85218-224-7 .

Web links