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Dye coupler is present in chromogenic film and paper used in photography, 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 than those for film use, but some modern films (such as Fujichrome Provia films) use variants of couplers that were originally designed for paper use to further improve the image permanence.

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