Photography was invented in 1825; this technique became accessible to the general public by 1839 with the advent of the daguerreotype, a direct-positive process that made it possible to capture an image. Later, three supports for recording an image co-existed:
- paper, with the first black and white print made in 1840, then the arrival of color in 1862 thanks to the invention of heliochromy.
- glass, which appeared in 1847 and was used by more people starting in 1854. Color started to be developed on this support in 1891.
- cellulose, with the first black and white negative in 1889, then the color negative in 1930, thanks to the invention of the slide.
All these media are particularly sensitive to humidity but can be very long-lived if they are kept in dry air and at a low temperature. Glass plates, which are particularly fragile, spurred a vigorous policy of digitization to avoid them being handled.