Concern about fading in photography is as old as photography itself, and dates at least to a well-known "Fading Committee" established by the Photographic Society of London in 1855.
This 1994 photograph had been framed with an oval frame. Note how the area exposed to light has changed.
But the photos we are all most concerned about aren't quite that old! They date from 1936, with the introduction of Kodachrome film for 35mm slides, to about 1990, and it's these photos that are particularly in danger.
These photos were printed using a number of different variations on what is called a chromogenic process. That simply means that the surface on which the print is made does not already contain the dyes necessary to make the colors required. Rather, this process relies on a number of chemicals and chemical reactions to create the dyes, on the fly, at the time of processing. And it is the combination of dyes — typically, cyan (blue), magenta (red), and yellow — that creates the final colors we see in a color photo.
Unfortunately, these dyes — that is, these chemical reactions — are inherently unstable. In fact, they begin to degrade as soon as the photo is printed! And light hitting a photo — nearly any kind of visible light — simply accelerates this process. This is why packages of film have typically carried disclaimers about the fact that colors may fade over time.
This film box, bought in November 2008, carries the disclaimer "Since color dyes may change in time, Walgreens cannot warranty this film against any change in color."
Typically, there are two effects: a loss of detail in general, particularly in the highlights, and a color shift. As the magenta dye is most unstable when exposed to light, compared to the other two dyes, the result is a photo that can shift to a slightly greenish cast.
Over the last 50 years, there have been many different chromogenic approaches to making prints. As the work of image permanence pioneer Henry Wilhelm has shown, these approaches do vary widely in terms of potential image permanence. Unfortunately, the most popular of these — for example, Ektacolor-processed prints from the 1960's and 1970's — have tended to have significant fading problems when exposed to light.
This photo was slightly faded, and correction was straightforward under ScanCafe's standard service.
Prior to the availability of scanning and digital photography software, if your photos were faded you were largely out of luck.That's not true any more!
Depending on the degree of fading, an image can be scanned and then digitally adjusted using a variety of photographic management software tools, like the ones ScanCafe technicians use. However, if your photos are severely faded, it can be challenging to bring them back to life — so it's definitely in your interest to hurry.
Source: http://www.scancafe.com/image-preservation/fading
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