Color photographs possess a poor stability towards light, chemicals heat and humidity. As a consequence, the colors of photographs deteriorate with time. Because of the complexity of processes that cause the dyes to fade, it is impossible to restore the images by chemical means. It is therefore attempted to restore faded color films by means of digital image processing.
"Restoration Of Faded Color Photographs By Digital Image Processing", Proc. SPIE 1135, Image Processing III, (11 October 1989); doi: 10.1117/12.961640; https://doi.org/10.1117/12.961640