A photograph also known as a photo is an image created by light falling on a photosensitive surface, usually photographic film or an electronic image sensorsuch as a CCD or a CMOS chip. Most photographs are created using a camerawhich uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would see.
The process and practice of creating such images is called photography. Some countries have laws against the production or distribution of certain types of photograph. 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 daguerreotypeafter himself. Its existence was announced to the world on 7 January but working details were not made public until 19 August. Other inventors soon made improvements which reduced the required exposure time from a few minutes to a few seconds, making portrait photography truly practical and widely popular.
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 All types of pics practical.
By the end of the s the daguerreotype had been replaced by the less expensive and more easily viewed ambrotype and tintypeAll types of pics made use of the recently introduced collodion process.
Glass plate collodion negatives used to make prints on 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 Refinements of the gelatin process have remained the primary black-and-white photographic process to this day, differing primarily in the sensitivity of the emulsion and the support material used, which was originally glass, then a variety of flexible plastic filmsalong with various types of paper for the final prints.
Color photography is almost as old as black-and-white, All types of pics early experiments including John Herschel 's Anthotype prints inthe pioneering work of Louis Ducos du Hauron in the s, and the Lippmann process unveiled inbut for many years color photography remained little more than a laboratory curiosity. It first became a widespread commercial reality with All types of pics introduction of Autochrome plates inbut the plates were very expensive and not suitable for casual snapshot-taking with hand-held cameras.
The All types of pics saw the introduction of Kodachrome and Agfacolor Neuthe first easy-to-use color films of the modern multi-layer chromogenic type. These early processes produced transparencies for use in slide projectors and viewing devices, but color prints became increasingly popular after the introduction of chromogenic color print paper in the s.
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. Non-digital photographs are produced with a two-step chemical process.
To produce a positive image, the negative is most commonly transferred ' printed ' onto photographic paper. Printing the negative onto transparent film stock is used to manufacture motion picture films.
Alternatively, the film is processed to invert the negative image, yielding positive transparencies.
Such positive images are usually mounted in frames, called slides. Before recent advances in All types of pics photography, transparencies were widely used by professionals because of their sharpness and accuracy of color rendition. Most photographs published in magazines were taken on color transparency film. Originally, all photographs were monochromatic or hand-painted in color. Although methods for developing color photos were available as early asthey did not become widely available until the s or s, and even so, until the s All types of pics photographs were taken in black and white.
Since then, color photography has dominated popular photography, although black and white is still used, being easier to develop than color. Panoramic format images can be taken with cameras like the Hasselblad Xpan on standard film.