Editing Photograph (section)

==History==
{{Main|History of photography}}
The first permanent photograph, a contact-exposed copy of an engraving, was made in 1822 using the [[Bitumen of Judea|bitumen]]-based "[[heliography]]" process developed by [[Nicéphore Niépce]]. The first photographs of a real-world scene, made using a [[camera obscura]], followed a few years later at Le Gras, France, in 1826, but Niépce's process was not sensitive enough to be practical for that application: a camera [[Exposure (photography)|exposure]] lasting for hours or days was required.<ref name="utexas">{{cite web |title=The First Photograph - Heliography |url=http://www.hrc.utexas.edu/exhibitions/permanent/wfp/heliography.html |quote=from Helmut Gernsheim's article, "The 150th Anniversary of Photography," in History of Photography Vol. I, No. 1, January 1977: ... In 1822, Niépce coated a glass plate ... The sunlight passing through ... This first permanent example ... was destroyed ... some years later. |access-date=29 September 2009 |archive-url=https://web.archive.org/web/20091006135924/http://www.hrc.utexas.edu/exhibitions/permanent/wfp/heliography.html |archive-date=6 October 2009 |url-status=dead }}</ref> In 1829, Niépce entered into a partnership with [[Louis Daguerre]], and the two collaborated to work out a similar, but more sensitive, and otherwise improved process.

[[File:View from the Window at Le Gras, Joseph Nicéphore Niépce, uncompressed UMN source.png|thumb|left|''[[View from the Window at Le Gras]]'', 1826 by [[Joseph Nicéphore Niépce]]]]

After Niépce's death in 1833, Daguerre concentrated on [[silver halide]]-based alternatives. He exposed a silver-plated copper sheet to iodine vapor, creating a layer of light-sensitive [[silver iodide]]; exposed it in the camera for a few minutes; developed the resulting invisible [[latent image]] to visibility with mercury fumes; then bathed the plate in a hot salt solution to remove the remaining silver iodide, making the results light-fast. He named this first practical process for making photographs with a camera, the [[daguerreotype]], after himself. Its existence was announced to the world on 7 January 1839, but working details were not made public until 19 August that year. Other inventors soon made drastic improvements that reduced the required amount of exposure time from a few minutes to just a few seconds, making portrait photography truly practical and widely popular during this time.

The daguerreotype had shortcomings, notably the fragility of the mirror-like image surface and the particular viewing conditions required to see the image properly. Each was a unique, opaque positive that could only be duplicated by copying it with a camera. Inventors set about working out improved processes that would be more practical. By the end of the 1850s, the daguerreotype had been replaced by the less expensive and more easily viewed [[ambrotype]] and [[tintype]], which made use of the recently introduced [[collodion process]]. Glass plate collodion negatives used to make prints on [[Albumen print|albumen paper]] soon became the preferred photographic method and held that position for many years, even after the introduction of the more convenient [[gelatin process]] in 1871. Refinements of the gelatin process have remained the primary [[black-and-white]] photographic process to this day, differing primarily in the sensitivity of the [[photographic emulsion|emulsion]] and the support material used, which was originally glass, then a variety of [[film base|flexible plastic films]], along with various types of paper for the final prints.
[[File:Kauppatori Kolera-altaan luona - G30718 - hkm.HKMS000005-km0000phjs.jpg|thumb|The [[Market Square, Helsinki|Market Square]] of [[Helsinki]], in the 1890s]]

Color photography is almost as old as [[black-and-white]], with early experiments including [[John Herschel]]'s [[Anthotype]] prints in 1842, the pioneering work of [[Louis Ducos du Hauron]] in the 1860s, and the [[Lippmann plate|Lippmann process]] unveiled in 1891, but for many years color photography remained little more than a laboratory curiosity. It first became a widespread commercial reality with the introduction of [[Autochrome]] plates in 1907, but the plates were very expensive and not suitable for casual snapshot-taking with hand-held cameras. The mid-1930s saw the introduction of [[Kodachrome]] and [[Agfacolor|Agfacolor Neu]], the first easy-to-use color films of the modern multi-layer [[chromogenic]] type. These early processes produced transparencies for use in [[slide projector]]s and viewing devices, but color prints became increasingly popular after the introduction of chromogenic color print paper in the 1940s. The needs of the motion picture industry generated a number of special processes and systems, perhaps the best-known being the now-obsolete three-strip [[Technicolor]] process.