Colour photography was explored beginning in the mid-1800s. Early experiments in colour could not fix the photograph and prevent the colour from fading. The first permanent colour photo was taken in 1861 by the physicist James Clerk Maxwell. Maxwell made contributions to the area of optics and colour vision, is credited with the discovery that colour photographs could be formed using red, green, and blue filters.
He had the photographer Thomas Sutton photograph a tartan ribbon three times, each time with a different colour filter over the lens. The three images were developed and then projected onto a screen with three different projectors, each equipped with the same colour filter used to take its image. When brought into focus, the three images formed a full-colour image. The three photographic plates now reside in a small museum at 14 India Street, Edinburgh, the house where Maxwell was born. One of the early methods of taking colour photos was to use three cameras. Each camera would have a colour filter in front of the lens. This technique provides the photographer with the three basic channels required to recreate a colour image in a darkroom or processing plant. Russian photographer Sergei Mikhailovich Prokudin-Gorskii developed another technique, with three colour plates taken in quick succession. The practical application of the technique was held back by the very limited colour response of early film; however, in the early 1900s, following the work of photochemists such as H. W. Vogel, emulsions with adequate sensitivity to green and red light, at last, became available.
The first colour plate, Autochrome, invented by the French Lumière brothers, reached the market in 1907. It was based on a ‘screen plate filter made of dyed dots of potato starch and was the only colour film on the market until German Agfa introduced the similar Agfacolor in 1932. In 1935, American Kodak introduced the first modern ‘integrated tri -pack’ colour film, Kodachrome, based on three coloured emulsions. This was followed in 1936 by Agfa’s Agfacolor Neue. Unlike the Kodachrome tri-pack process the colour couplers in Agfacolor Neue were integral with the emulsion layers, which greatly simplified the film processing. Most modern colour films, except Kodachrome, are based on the Agfacolor Neue technology. Instant colour film was introduced by Polaroid in 1963. Colour photography may form images as a positive transparency, intended for use in a slide projector or as colour negatives, intended for use in creating positive colour enlargements on specially coated paper. The latter is now the most common form of film non -digital colour photography owing to the introduction of automated photo printing equipment.
Colour photography is photography that uses media capable of preserving colours and is produced chemically during the photographic processing phase. It is often contrasted with black-and-white photography, which uses media capable only of showing shades of grey and does not include hand-coloured photographs. Some examples of colour photography include Prints, colour negatives, transparencies i.e. 35mm colour slides, roll films, and sheet films.
The first modern ‘integrated tri -pack’ colour film, Kodachrome, was introduced in 1935 based on three coloured emulsions. Most modern colour films, except Kodachrome, are based on technology developed for Agfacolor. In this newer technology, chromogenic dye couplers are already within the emulsion layers, rather than having to be carefully diffused during Development. Instant colour film was introduced by Polaroid in 1963.
There are basically two color systems:
1. Additive
The colours are added as coloured lights. In this system, the most common set of primary colours is red, green and blue. Maxwell’s experiment was of this type, as are screen-plate methods, such as Autochrome. Modern digital photographs seen on a VDG are also viewed by the addition of light from an RGB phosphor array.
2. Subtractive
Colours are subtracted from white light by dyes or pigments. In this system, the most common set of primary colours is cyan, magenta and yellow. Ducos du Hauron made several pictures by this method in the late 1800s.
Several commercial print methods were devised using the subtractive technique during the 1930s, for printing from ‘separation negatives’. Kodachrome was the first commercially available ‘integrated tri-pack film of this type.
There are two main types of color film in current use:
- Colour negative film forms a negative image when exposed, which is fixed during development. This is then exposed onto photographic paper to form a positive image.
- Colour reversal film, also known as slide film, forms a negative image when exposed, which is reversed to a positive image during development. The film can then be projected onto a screen.
However, it is important to understand that colour photographic materials are not permanent and by nature is unstable. Chromogenic colour photographs, for example, are composed of yellow, magenta, and cyan organic dyes which fade at different rates. Even when in dark storage and enclosed in the proper archival materials, deterioration is unavoidable, but fading, colour shifting, and discolouration can be prolonged when given the proper preservation care. Colour photography may form images as a positive transparency, intended for use in a slide projector or as colour negatives, intended for use in creating positive colour enlargements on specially coated paper. The latter is now the most common form of film non -digital colour photography owing to the introduction of automated photo printing equipment.
