** *"Colour film" redirects here. For the motion picture

"Colour film" redirects here. For the motion picture equivalent, see Color film (motion picture).
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.

Different types of color photographic processes
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.

Modern color film
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.

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.
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. Basic color systems

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. Main types of color film in current use

Preservation Issues
Numerous factors can deteriorate and even destroy photographs. Some examples include:
However, it is important to understand that color photographic materials 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 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 effect 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.

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
Disasters and emergencies
Dark fading
Light fading
Highlight staining Ideal storage environment
The usage of enclosures is the easiest method of preserving photographic materials from being destroyed by handling and 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 14523:1999(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.
It is recommended that each individual item has its own enclosure and that each enclosure chosen for a photograph is of an appropriate size. Archival enclosures may come in two different forms: paper or plastic. Choosing either option has its advantages and disadvantages.
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.

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, but also porous quality protects photographs from humidity and gaseous pollutants. However, for images to be viewed, they must be removed from its enclosure which puts the materials at risk for mishandling and 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 and reduces direct contact with the materials. Plastic is also less resistant to tears in comparison to paper. However, some disadvantages include proneness to static electricity and risk of ferrotyping (in other words, can trap moisture and cause materials to stick to one another). Recommended storage

U.S. Patent 2,059,884  — Color photography Patents

See also

George Eastman
William Eggleston
Frederick Lanchester
Gabriel Lippmann
Luis Marden
Stephen Shore People

Color film (motion picture)
Chromogenic
Color printing
Color television
Film colorization
Hand-colouring
Potassium ferricyanide
Timeline of invention Other topics

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Library of Congress List of Photographic Preservation Supplies