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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| History of photography | 6/7 | https://en.wikipedia.org/wiki/History_of_photography | reference | science, encyclopedia | 2026-05-05T04:00:07.060798+00:00 | kb-cron |
A practical means of color photography was sought from the very beginning. Results were demonstrated by Edmond Becquerel as early as the year of 1848, but exposures lasting for hours or days were required and the captured colors were so light-sensitive they would only bear very brief inspection in dim light. The first 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. 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, a process inventors and brothers Auguste and Louis Lumière began working on in the 1890s and commercially introduced in 1907. It was based on one of Louis Duclos du Haroun'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 of red, blue, and green 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 with roughly five million previously dyed potato grains per square inch added to the surface. Then through the use of a rolling press, five tons of pressure were used to flatten the grains, enabling every one of them to capture and absorb color and their microscopic size allowing the illusion that the colors are merged. The final step was adding a coat of the light-capturing substance silver bromide, after which a color image could be imprinted and developed. In order to see it, reversal processing was used to develop each plate into a transparent positive that could be viewed directly or projected with an ordinary projector. One of the drawbacks of the technology was an exposure time of at least a second in bright daylight, with the time required quickly increasing in poor light. An indoor portrait required several minutes with the subject stationary. This was because the grains absorbed color fairly slowly, and a filter of a yellowish-orange color was required to keep the photograph from coming out excessively blue. Although necessary, the filter had the effect of reducing the amount of light that was absorbed. Another drawback was that the image could only be enlarged so much before the many dots that made up the image would become apparent. 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 the few color print and slide films still being made in 2015 all use the multilayer emulsion approach pioneered by Kodachrome.
== Development of digital photography ==
In 1957, a team led by Russell A. Kirsch at the National Institute of Standards and Technology developed a binary digital version of an existing technology, the wirephoto drum scanner, so that alphanumeric characters, diagrams, photographs and other graphics could be transferred into digital computer memory. One of the first photographs scanned was a picture of Kirsch's infant son Walden. The resolution was 176x176 pixels with only one bit per pixel, i.e., stark black and white with no intermediate gray tones, but by combining multiple scans of the photograph done with different black-white threshold settings, grayscale information could also be acquired. The charge-coupled device (CCD) is the image-capturing optoelectronic component in first-generation digital cameras. It was invented in 1969 by Willard Boyle and George E. Smith at AT&T Bell Labs as a memory device. The lab was working on the Picturephone and on the development of semiconductor bubble memory. Merging these two initiatives, Boyle and Smith conceived of the design of what they termed "Charge 'Bubble' Devices". The essence of the design was the ability to transfer charge along the surface of a semiconductor. It was Dr. Michael Tompsett from Bell Labs however, who discovered that the CCD could be used as an imaging sensor. The CCD has increasingly been replaced by the active pixel sensor (APS), commonly used in cell phone cameras. These mobile phone cameras are used by billions of people worldwide, dramatically increasing photographic activity and material and also fueling citizen journalism.