A Glossary of Conventional Color and Digital Photographic Printing
This glossary lists the most relevant printmaking processes for conventional color and digital photography. Relevance is subjective and, by necessity, so is this list. Excluded are many processes that were technological breakthroughs or otherwise historically significant but are seldom found in collections of fine art photography. The definitions strive to be non-technical, presenting terms that are directly analogous to conventional "black and white" process names that are already familiar to AIPAD members such as "gelatin silver", "albumen," "platinum" etc. Often these processes are better known by proprietary methods and materials. In these cases, some of the key brands names, manufacturers and product introduction dates are listed.
-Paul Messier, Conservator of Photographs
Assembly (also called Pigment or Carbon)
Color prints made by the assembly process are comprised of at least three layers of pigmented gelatin. Each of the three layers contains one of the subtractive primary colors, cyan, yellow and magenta, which are superimposed one atop the other. Prints made by the assembly process are usually highly stable and lightfast due to the use of inorganic pigments versus organic dyes often used in other color processes.
Autotype: Carbro, 1912. Fresson: Quadichrome, 1951. UltraStable: Pigment Print, 1991.
Chromogenic
Chromogenic photographs are made using an emulsion with image forming layers containing either cyan, yellow or magenta dye. During processing, light sensitive silver halide is chemically developed and linked to the formation of each of the three dyes through chemical compounds known as "couplers." Once the silver serves its role in catalyzing the formation of the dyes, it is removed leaving a purely dye-based image. Traditionally chromogenic prints have poor stability due to the nature of the dyes and residual chemistry. Within the past 10-15 years, manufacturers have made progress producing more permanent chromogenic prints. Computer controlled lasers (or other light sources) can be used to expose chromogenic papers as in Lambda printers, produced by the Durst Company or Lightjet printers, made by Océ Display Graphics Systems. "C-print" is a common misnomer that often refers to a chromogenic print or to any color photographic print in general.
Agfa: Agfacolor, 1936. Kodak: Kodochrome, 1935; Kodacolor, 1942. Fuji: Crystal Archive, 1998.
Dye diffusion transfer
Following exposure, light sensitive silver halide is converted to metallic silver which then inhibits the transfer of dye from a "negative" to a receiver sheet. An image is formed by the cyan, yellow and magenta dyes that are allowed to "diffuse and transfer" to the receiver. This technology is widely used for so called "instant" prints.
Polaroid: Polacaolor, 1963; SX-70, 1972.
Dye imbibition
Corresponding to each of the primary colors, three film matrices are used to transfer cyan, yellow and magenta dye to a receiver sheet. Often this receiver sheet is an ordinary piece of gelatin silver paper that has been fixed and washed without being exposed. Partially owing to the fact that there is no residual processing chemistry and due to the relatively wide variety of suitable dyes, dye imbibition prints are very stable as compared to chromogenic prints and some other conventional color processes.
Kodak: Eastman Wash Off Relief, 1935; Dye Transfer, 1945.
Inkjet
Inkjet prints are formed by "spraying" ink droplets through nozzles onto a receiver sheet. The process uses between four to eight (or more) different dyes or pigments that are based on the subtractive primary colors of cyan, yellow and magenta plus black. A purely digital process, there are no light sensitive materials used in the production of inkjet prints. Starting in the late 1980's, inkjet prints were typically dye-based and had major permanence issues when exposed to light and moisture. Over the past five to seven years, many manufacturers have introduced pigment-based ink sets that have outstanding permanence, rivaling or exceeding conventional color prints made by the assembly process. "Giclée" is a term developed in the late 1980's to market inkjet prints, mostly for fine art applications.
IRIS Graphics: Iris Print, 1987. Epson pigment-based inks: Colorfast, 2000; UltaChrome K3, 2005.
Screen filter
Displayed much like a transparency or negative, screen filter photographs are viewed using transmitted light. Silver particles selectively block light from passing through either red, green and blue filters bound onto a transparent substrate, usually glass. A color image is formed by mixing the balance of light allowed to pass through the filters. The dyes used in the filters are typically quite light sensitive, causing images made using this technique to be susceptible to rapid fading if displayed inappropriately.
Lumiere: Autochrome, 1907.
Silver dye bleach
A silver-based image, formed following exposure to light, is used to selectively bleach cyan, yellow and magenta dye in each of three layers. Following the bleaching of the dye, the silver is removed through processing. The image is formed by dyes that remain. Generally, these dyes are fairly stable, certainly more so than the dyes used in the chromogenic processes.
Ilford: Cibachrome, 1963; Ilfochrome 1991.
Additional Information
Color Timeline (PDF 54 K)
