Dye coupler

As a color coupler is called colorless or provided with Azofarbstoffverbindungen substances in multilayer photographic films, the three primary colors according to the subtractive color mixing produce ( color coupler reaction) in the photograph; it involves a chromogenic method.

The color couplers in form of chromogenic development together with the oxidation products of the developer and the silver bromide water-insoluble, non-diffusible dyes.

In addition to color films also chromogenic black and white films can have color couplers which give a black and white image dye in the development.

Most color couplers have been patented by the respective manufacturers; Fuji Fujichrome Velvia for example, has three patented coupler, the so -called X -, V- and S- coupler.