The first photographic or heliographic procedure was invented by Niépce around 1824. The images were obtained with Judean bitumen, spread on a silver plate, after an exposure time of several days.

In 1829, Niépce associates Louis Jacques Mandé Daguerre in his research.
In 1832, they developed, from the residue of the distillation of lavender essence, a second procedure that produces images with an exposure time of a whole day.

Niépce died in 1833. Daguerre continues to work alone and invents, in 1838, the daguerreotype, the first method comprising a developing step. A silver plate coated with a thin layer of silver iodide was exposed in the camera obscura and then subjected to the action of mercury vapors that caused the appearance of the invisible latent image, formed in the course of exposure to light.

This development consisted of a large amplification of the light effect, so that the exposure time did not exceed 30 minutes. The fixate was obtained by immersion in water, saturated with sea salts.

Attached to appreciate the first photograph in the world.