View of a House and Garden - Early photography, Public domain image

Poitevin is best known for his invention of the collotype process, also known as photoglyptie or heliotype. This photographic printing process uses a gelatin-coated plate that is exposed to light through a negative and then developed with a chemical solution to produce a high-quality print. Poitevin began his career as a civil engineer, but became interested in photography in the early 1850s. He experimented with various printing processes, including carbon printing and photolithography, before developing the collotype process in 1855. The collotype process was initially used to reproduce artwork and illustrations, but quickly became popular for photographic printing. It was particularly suitable for printing high-quality images with fine detail and tonal range, and was widely used for commercial printing and book illustration in the late 19th and early 20th centuries. In addition to his work in photography, Poitevin also made significant contributions to the field of chemistry. He was particularly interested in the study of light-sensitive materials and developed new methods for the production of pigments and dyes. Poitevin's work had a significant impact on the development of photography and printing technology, and his collotype process remained in use well into the 20th century.