Late Nineteenth Century France

The popularisation of photography at the end of the nineteenth century

Photography has roots in remote antiquity with the discovery of the principle of the camera obscura and the observation that some substances are visibly altered by exposure to light. As far as is known, nobody thought of bringing these two phenomena together to capture camera images in permanent form until around 1800, when Thomas Wedgwood made the first reliably documented although unsuccessful attempt. In the mid-1820s, Joseph Nicéphore Niépce succeeded, but several days of exposure in the camera were required and the earliest results were very crude. Niépce's associate Louis Daguerre went on to develop the daguerreotype process, the first publicly announced photographic process, which required only minutes of exposure in the camera and produced clear, finely detailed results. It was commercially introduced in 1839, a date generally accepted as the birth year of practical photography.
The metal-based daguerreotype process soon had some competition from the paper-based calotype negative and salt print processes invented by Henry Fox Talbot. Subsequent innovations reduced the required camera exposure time from minutes to seconds and eventually to a small fraction of a second; introduced new photographic media which were more economical, sensitive or convenient, including roll films for casual use by amateurs; and made it possible to take pictures in natural color as well as in black-and-white.
The introduction of computer-based electronic digital cameras in the late 20th century soon revolutionized photography. During the first decade of the 21st century, traditional film-based photochemical methods were increasingly marginalized as the practical advantages of the new technology became widely appreciated and the image quality of moderately priced digital cameras was continually improved.

A practical means of color photography was sought from the very beginning. Results were demonstrated as early as 1848, but exposures lasting for hours or days were required and the colors were so light-sensitive they would only bear very brief inspection in dim light.
The first durable color photograph was a set of three black-and-white photographs taken through red, green and blue color filters and shown superimposed by using three projectors with similar filters. It was taken by Thomas Sutton in 1861 for use in a lecture by the Scottish physicist James Clerk Maxwell, who had proposed the method in 1855.^[22] The photographic emulsions then in use were insensitive to most of the spectrum, so the result was very imperfect and the demonstration was soon forgotten. Maxwell's method is now most widely known through the early 20th century work of Sergei Prokudin-Gorskii. It was made practical by Hermann Wilhelm Vogel's 1873 discovery of a way to make emulsions sensitive to the rest of the spectrum, gradually introduced into commercial use beginning in the mid-1880s.
Two French inventors, Louis Ducos du Hauron and Charles Cros, working unknown to each other during the 1860s, famously unveiled their nearly identical ideas on the same day in 1869. Included were methods for viewing a set of three color-filtered black-and-white photographs in color without having to project them, and for using them to make full-color prints on paper.
The first widely used method of color photography was the Autochrome plate, commercially introduced in 1907. It was based on one of Louis Ducos du Hauron's ideas: instead of taking three separate photographs through color filters, take one through a mosaic of tiny color filters overlaid on the emulsion and view the results through an identical mosaic. If the individual filter elements were small enough, the three primary colors would blend together in the eye and produce the same additive color synthesis as the filtered projection of three separate photographs. Autochrome plates had an integral mosaic filter layer composed of millions of dyed potato starch grains. Reversal processing was used to develop each plate into a transparent positive that could be viewed directly or projected with an ordinary projector. The mosaic filter layer absorbed about 90 percent of the light passing through, so a long exposure was required and a bright projection or viewing light was desirable. Competing screen plate products soon appeared and film-based versions were eventually made. All were expensive and until the 1930s none was "fast" enough for hand-held snapshot-taking, so they mostly served a niche market of affluent advanced amateurs.
A new era in color photography began with the introduction of Kodachrome film, available for 16 mm home movies in 1935 and 35 mm slides in 1936. It captured the red, green and blue color components in three layers of emulsion. A complex processing operation produced complementary cyan, magenta and yellow dye images in those layers, resulting in a subtractive color image. Maxwell's method of taking three separate filtered black-and-white photographs continued to serve special purposes into the 1950s and beyond, and Polachrome, an "instant" slide film that used the Autochrome's additive principle, was available until 2003, but all the color films for making prints and slides currently (2013) available use the multilayer emulsion approach pioneered by Kodachrome.