Dye couplers
Encyclopedia
Dye coupler is present in chromogenic
Chromogenic
Chromogenic refers to color photographic processes in which a traditional silver image is first formed, and then later replaced with a colored dye image.- Description :...

 film
Photographic film
Photographic film is a sheet of plastic coated with an emulsion containing light-sensitive silver halide salts with variable crystal sizes that determine the sensitivity, contrast and resolution of the film...

 and paper
Photographic paper
Photographic paper is paper coated with light-sensitive chemicals, used for making photographic prints.Photographic paper is exposed to light in a controlled manner, either by placing a negative in contact with the paper directly to produce a contact print, by using an enlarger in order to create a...

 used in photography
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...

, primarily color photography. When color developer develops exposed silver-halide crystals, the developing agent molecules become oxidized, and the oxidized developer molecules react with dye coupler molecules to form dye in situ. Silver image is removed by subsequent bleach and fix processes, and the final image will consist of the dye images.

The dye coupler technology has seen considerable advancement since the beginning of modern color photography. In terms of image permanence, major film and paper manufacturers have continually improved the stability of the image dye by improving couplers, particularly since 1980s, so that the keeping property of the images are enhanced in modern color papers and films. Generally speaking, dye couplers for paper use are given more emphasis on the image permanence then those for film use, but some modern films (such as Fujichrome Provia
Provia
Provia is a brandname for a pair of daylight-balanced color reversal films produced by the Japanese film company Fujifilm. It is available in two speeds: 100/21° marketed as Fujichrome Provia 100F Professional [RDP III], and 400/27° marketed as Fujichrome Provia 400X Professional [RXP].Provia 100F...

films) use variants of couplers that were originally designed for paper use to further improve the image permanence.
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