Color photography
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- "Color film" redirects here. For the motion picture equivalent, see Color motion picture film.
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Color photography is photography that uses media capable of representing colors which are produced chemically during the photographic processing phase. It is contrasted with black-and-white photography, which uses media capable only of showing shades of gray, and does not include hand colored photographs. Some examples of color photography include prints, color negatives, transparencies and slides, and roll and sheet films.
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[edit] Different types of color photographic processes
The experimentation with creating photographs that mirrored the colors of real life began as early as 1861. It is important to be able to identify different photographic processes because each process may require different methods of preservation.
- 1861: The first known permanent color photograph is taken by James Clerk Maxwell
- 1877: Louis Ducos du Hauron experiments with subtractive color (see below)
- 1891: Lippmann process
- 1896: Joly color screen process
- 1907 (patented 1904): Autochrome
- 1908: Dufaycolor (color transparencies)
- 1908: Finlay Colour (color transparencies)[clarify]
- 1909–1915: Prokudin-Gorskii's color documentary photography in Russia
- 1920 (patented 1905): Tri-Color Carbro prints (by Louis Ducos du Hauron since 1862 and Charles Cros since 1867), it lasts to 1960 by Autotype
- 1935: Kodachrome (16mm motion picture film)
- 1936: Kodachrome (35mm still film)
- 1936: Agfacolor (transparency film)
- 1940: Ektachrome (slide film)
- 1942: Kodacolor (color negative process for still photography and later motion pictures)
- 1946: Dye transfer prints (imbibition process)
- 1965: Polacolor by Polaroid (dye diffusion transfer process)[clarify]
[edit] Modern color film
The first modern ("integrated tri-pack") color film, Kodachrome, was introduced by the Eastman Kodak Company in 1935, using three colored emulsions. Most modern color films, except Kodachrome, are based on technology developed for Agfacolor (as "Agfacolor Neue") in 1936. (In this newer technology, chromogenic dye couplers are already within the emulsion layers, rather than having to be carefully diffused in during development.) Instant color film was introduced by Polaroid in 1963.
[edit] Basic color systems
- Additive: The colors are added as colored lights. In this system, the most common set of primary colors is red, green and blue (RGB). Maxwell's experiment was of this type, as are screen-plate methods, such as Autochrome. Modern digital photographs seen on a computer monitor are also viewed by addition of light from an RGB phosphor array[clarify].
- Subtractive: Colors are subtracted from white light by dyes or pigments. In this system the most common set of primary colors is cyan, magenta, yellow and black (CMYK). 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 (see e.g. Coe, ref 1), for printing from "separation negatives". Kodachrome was the first commercially-available film of this type.
[edit] Main types of color film in current use
- Color negative film forms a negative (color-reversed) image when exposed, which is permanently fixed during developing. This is then exposed onto photographic paper to form a positive image.
- Color reversal film, also known as slide film, forms a negative image when exposed, which is reversed to a positive image during developing. The film can then be projected onto a screen.
[edit] Preservation Issues
[edit] What destroys color photographs
Numerous factors can deteriorate and even destroy photographs. Some examples include:
- High temperature and high relative humidity (RH)
- Air pollution and dirt
- Light exposure
- Biological threats such as fungi and insects
- Residual processing chemicals
- Base and emulsion deterioration
- Handling and usage
- Improper storage and enclosures
However, an important property of color photographic materials to understand is that they are not permanent and by nature are instable. Chromogenic color 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, color shifting, and discoloration can be delayed when given the proper preservation care.
Three signs of age that affect color photography are:
- Dark fading
- Light fading
- Highlight staining
Dark fading occurs regardless of the procedures taken to preserve a photograph and is unavoidable. It is instigated by temperature and RH. Cyan dyes will typically fade more quickly, which will make the image appear too red in color.
Light fading occurs when materials are exposed to light, e.g. while on display. The intensity of the light source and ultraviolet (UV) rays will affect the rate of change and fade. Magenta dyes will typically fade the quickest.
Highlight staining occurs with older color photographic papers, and is a yellowing of the border and highlight areas of a photograph.
[edit] Ideal storage environment
In general, the colder the storage, the longer the "life" of color photographs. Frost-free refrigeration, more commonly known as cold storage (below freezing) is one of the most effective ways to bring a halt to developing damage to color photographic materials. However, selecting this type of storage environment is costly and requires special training to remove items and return items. Therefore, cool storage (above freezing) is more common and less costly, which requires that the temperature is consistently between 10°C – 15°C (50°F – 60°F) with 30–40% relative humidity with special attention to dew point to eliminate concerns for condensation. General dark storage in light tight enclosures and storage boxes is always advised for individual items. When materials are exposed to light during handling, usage, or display - light sources should be UV-filtered and intensity kept at minimum. In storage areas, 200–400 lux is recommended.
[edit] Recommended storage
The usage of enclosures is the easiest method of preserving photographic materials from being damaged through handling and light exposure. All protective materials should pass the Photographic Activity Test (PAT) as described both by the American National Standards Institute (ANSI) in standard IT9.2-1988, and the International Organization for Standardization (ISO) in standard 18916:2007(E), Photography – Processed Photographic Materials – Photographic Activity Test for Enclosure Materials. The PAT is an archival science test that determines what kind of enclosures will preserve, prevent, and/or prolong from further deterioration while in storage.
The recommended use of archival enclosures includes each item having its own enclosure and that each enclosure is of the appropriate size. Archival enclosures may come in two different forms: paper or plastic. Choosing either option has its advantages and disadvantages.
- Paper enclosures should be non-acidic, lignin-free paper and may come in either buffered or non-buffered stock. An advantage of paper is that it is generally less costly than plastic enclosures. The opaque quality of paper protects photographs from light exposure, and the porous quality protects photographs from humidity and gaseous pollutants. However, for images to be viewed, they must be removed from the enclosure, putting the materials at risk for mishandling and/or vandalism.
- Archival quality plastic enclosures are made of uncoated polyester, polypropylene, or polyethylene. The transparent quality of plastic lends itself to easier access to the image because there is no extra step to remove the photograph. Plastic is also less resistant to tears in comparison to paper. Some disadvantages include being prone to static electricity and a risk of ferrotyping (the act of moisture becoming trapped between the enclosure and item, causing the materials to stick to one another).
After photographic materials are individually enclosed, housing or storage containers provide another protective barrier such as folders and boxes made from archival paperboard as addressed in ISO Standards 14523 and 10214. Sometimes these containers have to be custom-made in order to properly store odd sizes. In general, flat storage of in boxes is recommended because it provides more stable support, particularly for materials that are in more fragile condition. Still, boxes and folders should never be over-filled with materials.
[edit] Patents
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- U.S. Patent 2,059,884 — Color photography
[edit] See also
[edit] People
- George Eastman
- William Eggleston
- Frederick Lanchester
- Gabriel Lippmann
- Luis Marden
- Stephen Shore
- Sergey Prokudin-Gorsky
[edit] Other topics
- Color film (motion picture)
- Chromogenic
- Color printing
- Color television
- Film colorization
- Hand-colouring
- Potassium ferricyanide
- Timeline of invention
[edit] References
- Coe, Brian, Colour Photography: the first hundred years 1840-1940, Ash & Grant, 1978.
- Coote, Jack, The Illustrated History of Colour Photography, Fountain Press Ltd., 1993, ISBN 0-86343-380-4
- Eastman Kodak Company. (1979). Preservation of photographs. Kodak publication, no. F-30. [Rochester, N.Y.]: Eastman Kodak Co.
- Great Britain, & Paine, C. (1996). Standards in the museum care of photographic collections 1996. London: Museums & Galleries Commission. ISBN 0948630426
- Keefe, L. E., & Inch, D. (1990). The life of a photograph: archival processing, matting, framing, storage. Boston: Focal Press. ISBN 0240800249 9780240800240
- Lavédrine, B., Gandolfo, J.-P., & Monod, S. (2003). A guide to the preventive conservation of photograph collections. Los Angeles: Getty Conservation Institute. ISBN 0892367016 9780892367016
- Photograph preservation and the research library. (1991). Mountain View, Ca: The Research Libraries Group. ISBN 0879852127
- Reilly, J. M. (1998). Storage guide for color photographic materials. Albany, N.Y.: University of the State of New York ... [et al.].
- Ritzenthaler, M. L., Vogt-O'Connor, D., & Ritzenthaler, M. L. (2006). Photographs: archival care and management. Chicago: Society of American Archivists. ISBN 1931666172 9781931666176
- Sipley, Louis Walton, A Half Century of Color, Macmillan, 1951
- Time-Life Books. (1982). Caring for photographs: display, storage, restoration. Life library of photography. Alexandria, Va: Time-Life Books. ISBN 0809444208
- Weinstein, R. A., & Booth, L. (1977). Collection, use, and care of historical photographs. Nashville: American Association for State and Local History. ISBN 091005021X
- Wilhelm, H. G., & Brower, C. (1993). The permanence and care of color photographs: traditional and digital color prints, color negatives, slides, and motion pictures. Grinnell, Iowa, U.S.A.: Preservation Pub. Co. ISBN 0911515003
- Wythe, D. (2004). Museum archives: an introduction. Chicago: Society of American Archivists. ISBN 1931666067 9781931666060
[edit] External links
[edit] General
- Internet Resources compiled by the Northeast Document Conservation Center
- "Care and Handling and Storage of Photographs" by Mark Roosa (IFLA)
- Conservation Register
- Image Permanence Institute
- Library of Congress - Information Leaflet: Photographs
- National Archives and Records Administration - Cold Storage Handling Guidelines
- National Park Service. Conserve-O-Gram (select PDF versions on menu)
- Henry Wilhelm
