Encyclopedia

Photo Hunt An arcade game, based on touch-screen technology, usually found in dimly lit dive venues scattered amongst the urban sprawl. P-Hunt is commonly found in close proximity to a Jukebox, pool tables and other activities.
Photo instrumentation Photo instrumentation refers to recording information of a diagnostic nature via a photographic process. This term is typically associated with high speed still, motion picture and video cameras, and other specialized devices recording an object to determine it's reaction to some kind of force or event.
Photo Marketing Association As a professional trade association, PMA® helps the worldwide photo imaging community achieve business success and adapt to new technologies. PMA continues its 82-year legacy of connecting photo imaging businesses to a network of knowledge and support.
Photo printer A photo printer is a printer (usually an inkjet printer) that is specifically designed to print high quality digital photos on photo paper. These printers usually have a very high number of nozzles and are capable of printing droplets as small as 1 picoliter.
Photo sharing Photo sharing is the publishing or transfer of a user's digital photos online, thus enabling the user to share them with others (whether publicly or privately). This functionality is provided through both websites and applications that facilitate the upload and display of images.
Photo Story Microsoft Photo Story is a freeware that allows you to create a show and tell presentation using your digital photos. Once a photo story has been made it can be played on Windows Media Player or burned to a DVD or CD.
Photoacoustic Imaging Photoacoustic Imaging is a non-invasive medical imaging technique used to detect vascular disease, skin abnormalities, and some types of cancer. It works by flashing a laser at low energy with a near infrared wavelength onto a target area.
Photoacoustic spectroscopy Photoacoustic spectroscopy is based on the photoacoustic effect. The discovery of the photoacoustic effect dates to 1880 when Alexander Graham Bell showed that thin discs emitted sound when exposed to a beam of sunlight that was rapidly interrupted with a rotating slotted disk.
Photoallergy Photoallergy is a form of allergic contact dermatitis in which the allergen must be activated by light to sensitize the allergic response, and to cause a rash on subsequent exposure. The second and subsequent exposures produce photoallergic skin conditions which are often eczematous.
Photoassimilate Photoassimilate - refers to any number of biological compounds formed by Assimilation (biology) using Light-dependent reactions. This term is most commonly used to refer to the energy-storing sugars produced by Photosynthesis in the leaves of plants.
Photobacterium phosphoreum Photobacterium phosphoreum or Vibrio phosphoreum is a Gram-negative luminescent bacterium living in symbiosis with marine organisms. It can emit blueish-green light (490 nm) thanks to a chemical reaction between FMN, luciferin and molecular oxygen catalysed by an enzyme called Luciferase.
Photobiology Photobiology is the scientific study of the interactions of light and living organisms. The field includes the study of photosynthesis, photomorphogenesis, visual processing, circadian rhythms, bioluminescence, and ultraviolet radiation effects.
Photobiomodulation Photobiomodulation, also known as low level laser therapy (LLLT), cold laser therapy, and laser biostimulation, is a controversial medical and veterinary technique in which exposure to low-level laser light is claimed to enhance tissue growth and have other beneficial effects. The technique is also known by the more ambiguous terms phototherapy and laser therapy, which may also be used to describe other medical techniques.
Photoblaster The Nickelodeon PhotoBlaster (Long Hall Technologies model N6800) is a compact "kid's" camera which has the useful feature of being able to take 4 images onto a single 35mm frame of film, one shot at a time. The camera uses standard 35mm film, and has a built-in viewfinder and flash, and works by shooting with 2 fixed lenses.
Photobleaching Photobleaching is the destruction of a photochemical fluor by high-intensity light. In microscopy, photobleaching may complicate the observation of fluorescent molecules, since they will eventually be destroyed by the light exposure necessary to stimulate them into fluorescing.
Photoblog A photoblog (or photolog) is a form of photo sharing and publishing in the format of a blog, but differentiated by the predominant use of and focus on photographs rather than text. Photoblogging (the action of posting photos to a photoblog) gained momentum in the early 2000s with the advent of the moblog and cameraphones.
Photobucket Photobucket is an image hosting, video hosting, slideshow creation and photo sharing website. Photobucket is usually used for personal photographic albums, remote storage of avatars displayed on Internet forums, and storage of videos.
PhotoBox PhotoBox is an online photo processing service in the United Kingdom. Launched in 2000, it was the first such service to operate in the UK, and also subsequently the first UK service to be included in Microsoft's Windows XP Media Centre.
Photocathode In a photomultiplier or photodiode tube, a photocathode is a negatively charged electrode coated with a photosensitive compound. When this is struck by light, electrons are emitted due to the photoelectric effect.
Photoclinometry Photoclinometry is the process by which a 2-dimensional image of a surface is transformed into a surface map that represents different levels of elevation. It uses the shadows and light direction as reference points.
Photoconceptualism Photoconceptualism (or photo-conceptualism) is an artistic movement which emerged in Vancouver, British Columbia in the 1960s and 1970s. The term has been used to describe photographic output of a generation of artists trained in Vancouver including Jeff Wall, Rodney Graham, Ken Lum, Ian Wallace, Stan Douglas, Roy Arden, and Scott McFarland.
Photoconductivity Photoconductivity is an optical and electrical phenomenon in which a material becomes more conductive due to the absorption of electro-magnetic radiation such as visible light, ultraviolet light, or gamma radiation. To be photoconductive a semiconductor must be in thermal equilibrium, which contains free electrons and holes.
Photocopylore Like email and chain letters, office technology has given new life to various forms of practical jokes, urban legends, and folklore. Photocopylore, or "xeroxlore," is the term given to these sometimes funny, sometimes offensive bits of human nonsense that roll off photocopiers.
Photocytes A Photocyte is a cell that specializes in catalyzing enzymes to produce light (bioluminescence). Photocytes typically occur in select layers of epithelial tissue, functioning singly or in a group, or as part of a larger apparatus (a photophore).
Photodegradation Photodegradation is degradation of a photodegradable molecule caused by the absorption of photons, particularly those wavelengths found in sunlight, such as infrared radiation, visible light and ultraviolet light. However, other forms of electromagnetic radiation can cause photodegradation.
Photodissociation Photodissociation (or photolysis) is a chemical reaction in which a chemical compound is broken down by photons. Photodissociation is not limited to visible light, but to have enough energy to break up a molecule; the photon is likely to be an electromagnetic wave with the energy of visible light or higher, such as ultraviolet light, x-rays and gamma rays.
Photodynamic therapy Photodynamic therapy (PDT), matured as a feasible medical technology in the 1980s at several institutions throughout the world, is a ternary treatment for cancer involving three key components: a photosensitizer, light, and tissue oxygen. It is also being investigated for treatment of psoriasis and acne, and is an approved treatment for wet macular degeneration.
Photoelectrochemical cell Photoelectrochemical cells or PEC's are solar cells and extract electrical energy from light, including visible light. Each cell consists of a semiconducting photoanode and a metal cathode immersed in an electrolyte.
Photoelectrolysis Photoelectrolysis occurs in a photoelectrochemical cell when light is used for electrolysis. In other words, photoelectrolysis is the conversion of light into a current, and then the division of a molecule using that current.
Photoengraving Photoengraving also known as photo-chemical milling is a process of engraving using photographic techniques. The most common type of photoengraving involves using a material that is photosensitive and resistant to acids or other etching compounds.
Photoexcitation Photoexcitation is the mechanism of electron excitation by photon absorption, when the energy of the photon is too low to cause photoionization.The absorption of photon takes place in accordance to the Planck's Quantum Theory.
Photofit "Photofit" is a technique used by the police for building up an accurate image of someone to fit a witness's description. Photographs, rather than drawings, of individual features are used to construct an image of a suspect.
Photoflash capacitor A photoflash capacitor is a low-capacitance, high-voltage capacitor used in flash cameras, professional flashes, and solid-state laser power supplies. Their typical purpose is to power a high voltage flash tube, which then illuminates a photographic target or optically pumps a laser rod.
Photogenic The term photogenic refers to a subject, generally human, that usually appears physically attractive or striking in photographs, regardless of their physical appearance in real life. Photogenic drawing, coined by William Fox Talbot, also describes the earliest method for recording camera images.
Photografting Photografting is a technique used in the study of polymers and more in specific polymeric biomaterials. Technically speaking it is the covalent incorporation of functional additives to a polymer matrix or polymer surface using a light-induced mechanism.
Photogram A photogram is a photographic image made (without a camera) by placing objects directly onto the surface of a photo-sensitive material such as photographic paper and then exposing it to light. The result is a silhouetted image varying in darkness based on the transparency of the objects used, with areas of the paper that have not received any light appearing light and those that have appearing dark, according to the laws of photosensitivity.
Photogrammetry Photogrammetry is a measurement technology in which the three-dimensional coordinates of points on an object are determined by measurements made in two or more photographic images taken from different positions (see stereoscopy).
Photograph A photograph (often shortened to photo) is a single image created using a record of light falling on a light-sensitive surface, usually photographic film or a CCD. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a faithful reproduction of what the human eye would see.
Photograph (Def Leppard song) Photograph is one of the most famous songs and 1983 single by British hard rock band Def Leppard from their multi-platinum album Pyromania. When released as a single later that year, it reached #1 on the Mainstream Rock charts and #12 on Pop Singles.
Photograph (Ringo Starr song) "Photograph" is a song written by Ringo Starr and George Harrison. It was released by Starr as a single in October 1973, reaching number eight and number one in the UK and US singles charts, respectively.
Photograph album A photographic album, or photo album, is a collection of a series of photographs, generally in a book. Some albums have compartments which the photos may be slipped in to; older style albums often were simply books of heavy paper which photos could be glued to or attached to with adhesive corners, or pages.
Photograph conservation Photograph conservation is the study of the physical care and treatment of photographic materials, including an in-depth understanding of how photographs are made, and the causes and prevention of deterioration. Conservators use this knowledge to treat photographic materials, stabilizing them from further deterioration, and sometimes restoring them for aesthetic purposes.
Photographer A photographer is a person who takes a photograph using a camera. This person is generally considered the artist, because he or she constructed the appearance of the product in the same way as any other visual artists.
Photographers of the American Civil Rights Movement Beginning with the murder of Emmett Till in 1955, photography and photographers played an important role in advancing the American Civil Rights Movement by documenting the public and private acts of racial discrimination against African Americans. This article focuses on these photographers and the role that they played in the movement between 1954 and 1968, particularly in the South.
Photographic developer In film developing, photographic developer (or just developer) is a chemical that makes the latent image on the film or print visible. It does this by reducing the silver halides that have been exposed to light to metals of elemental silver in the gelatine matrix.
Photographic film Photographic film is a sheet of plastic (polyester, nitrocellulose or cellulose acetate) coated with an emulsion containing light-sensitive silver halide salts (bonded by gelatin) with variable crystal sizes that determine the sensitivity and resolution of the film. When the emulsion is subjected to sufficient exposure to light (or other forms of electromagnetic radiation such as X-rays), it forms a latent (invisible) image.
Photographic filter In photography, a filter is a camera accessory consisting of an optical filter that can be inserted in the optical path. The filter can be a square or rectangle shape mounted on a holder accessory, or, more commonly, a glass or plastic disk with a metal or plastic ring frame, which can be screwed in front of the lens.
Photographic fixer Photographic fixer is a chemical used in the final step in the photographic processing of film or paper. The fixer removes the unexposed silver halide remaining on the negative or photographic paper, leaving behind the reduced metallic silver that forms the image.
Photographic lens A photographic lens (also known as objective lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.
Photographic magnitude Before the advent of photometers which accurately measure the brightness of astronomical objects, the apparent magnitude of an object was obtained by taking a picture of it with a camera. These images, made on photoemulsive film, were more sensitive to the blue end of the visual spectrum than the human eye or modern photometers.
Photographic mosaic In the field of photographic imaging, a photographic mosaic (also known under the term Photomosaic, a portmanteau of photo and mosaic, trademarked by Runaway Technology, Inc.) is a picture (usually a photograph) that has been divided into (usually equal sized) rectangular sections, each of which is replaced with another photograph of appropriate average color.
Photographic plate Photographic plates were one of the earliest forms of photographic film, in which a light-sensitive emulsion of silver salts was applied to a glass plate. This form of photographic emulsion largely faded from the consumer market in the early years of the 20th century, as more convenient and less fragile films were introduced.
Photographic processing Conventional photographic films and papers need to be chemically processed after they have been exposed in order to produce the desired negative or positive image. The general process is similar whatever the make of film or paper.
Photographic quantity The term photographic quantity (also known as photoquantity) refers to the amount of light received by a sensor, such as a camera, in dimensionless units that account for information lost by integration over the spectral response of the sensor, while otherwise preserving the linear relationship involved in the interaction of light through one or more exposures. The photoquantity is neither radiometric nor photometric.
Photographs and Notebooks 'Photographs and Notebooks' is a collection of British author Bruce Chatwin's photographs and notebooks which were made during his life when he was working on his various novels and travel books. It was published posthumously in 1993.
Photography Photography is the process of making pictures by means of the action of capturing light on a film. Light patterns reflected or emitted from objects are recorded onto a sensitive medium or storage chip through a timed exposure.
Photography in Australia The first photograph taken in Australia, a view of Bridge Street (now lost) is believed to have been taken by a visiting naval captain, Captain Augustin Lucas (1804-1854) in 1841, as indicated by a note published in the Australasian Chronicle for 13 April of that year. Lucas arrived in Sydney aboard the Justine, captained by his younger brother Francois Lucas.
Photography in New Zealand New Zealand photography began in the mid-19th century, when a number of photographers began documenting the country's natural beauty and people. Alfred Burton, of the Dunedin Burton Brothers, also travelled through many of the Pacific islands near New Zealand with the P&O Shipping line, in the early days of tourism through the region.
Photography triplet Photography or paint triplet is set of three photos or paints usually related to one event or developing some story. Many top art photographers using triplets to describe more complicated story or to attract the viewer by showing more related prints together.
Photogravure Photogravure is a type of intaglio printmaking initially developed in the 1830s by Henry Fox Talbot in England and Nicéphore Niépce in France. These were the first photographs, pre-dating daguerreotypes and the later silver-gelatin photos.
Photoheterotroph Photoheterotrophs (or photoorganotrophs) are heterotroph organisms which use light for energy, but cannot use carbon dioxide as their sole carbon source. Consequently, they use organic compounds from the environment to satisfy their carbon requirements.
Photohydrogen Photohydrogen is hydrogen produced with the help of artificial or natural light (Photolysis). This is how the leaf of a tree splits water molecules into hydrogen (to make carbohydrates) and oxygen (released into the air for us to breathe) NOVA scienceNOW - A 14 minute video of the NOVA broadcast about hydrogen fuel cell cars that aired on PBS, July 26, 2005.
Photochromatic glass Photochromatic glass, also known as smart glass is a material whose optical properties can be altered electrically. In the most common variation, a pane of glass is normally translucent, but when voltage is present between its surfaces, it becomes transparent.
Photoinhibition Photoinhibition is a reduction in a plant's (or other photosynthetic organism's) capacity for photosynthesis caused by exposure to strong light (above the saturation point). Photoinhibition is not caused by high light per se, but rather absorption of too much light energy compared with the photosynthetic capacity, i.
Photoionization detector A photoionization detector or PID uses an ultraviolet (UV) lightsource to break molecules to positively charged ions that can easily be counted with a detector. Ionization occurs when a molecule absorbs high energy UV light, which excites the molecule, and results in temporary loss of a negatively charged electron and the formation of positively charged ion.
Photojournalism Photojournalism is a particular form of journalism (the collecting, editing, and presenting of news material for publication or broadcast) that creates images in order to tell a news story. It is now usually understood to refer only to still images, and in some cases to video used in broadcast journalism.
Photokinema Phono-Kinema (some sources say Photo-Kinema) was a sound-on-disc system for motion pictures invented by Orlando Kellum. The system was used for a small number of short films, mostly made in 1921, of subjects such as actor Frederick Warde reading an original poem, labor leader Samuel Gompers speaking on labor issues, Judge Ben Lindsey on the need for a separate juvenile court system, Irvin S.
Photoluminescence Photoluminescence is a process in which a chemical compound absorbs a photon (electromagnetic radiation), thus transitioning to a higher electronic energy state, and then radiates a photon back out, returning to a lower energy state. The period between absorption and emission is typically extremely short, on the order of 10 nanoseconds.
Photolyase Photolyase is an enzyme that binds complementary DNA strands and breaks pyrimidine dimers that are typically caused by exposure to ultraviolet light. Pyrimidine dimers occur when a pair of thymine bases or cytosine bases on the same strand of DNA bind together, resulting in a 'bulge' of the DNA structure referred to as a lesion.
PhotoLoader PhotoLoader is a program by Casio that runs on Windows systems (above Windows 95) designed primarily for Casio digital cameras using USB connections. PhotoLoader is primarily designed for the purpose of copying picture, video, and audio files from the digital camera to a library folder stored on the computer by PhotoLoader and then organized in an HTML library file that is displayed by the system's default Web browser.
Photomagneton The photomagneton is a theoretical treatment of the unitary group in quantum field theory and quantum chemistry that effectively describes the experimentally observed inverse Faraday effect. When circularly polarized light travels through a plasma, the angular momentum associated to the circular motion of the photons induces an angular momentum in the electrons of the plasma.
Photomedicine Photomedicine is an interdisciplinary branch of medicine that involves the study and application of light with respect to health and disease. Photomedicine may be related to the practice of various fields of medicine including dermatology, surgery, dentistry, optical diagnostics, cardiology, and oncology.
Photometer In the broadest sense, a photometer is any instrument used to measure illuminance or irradiance. As applied in industrial photometry, a "photometer" is the general term covering instruments for detecting:
Photometric parallax method The photometric parallax method is a method of data analysis used in astronomy that uses the colours and apparent brightnesses of stars to infer their distances. It was used by the Sloan Digital Sky Survey to discover the Virgo super star cluster.
Photometric redshift A photometric redshift is an estimate for the distance of an astronomical object, such as a galaxy or quasar. The technique uses photometry (that is, the brightness of the object viewed through various standard filters, each of which lets through a relatively broad spectrum of colours, such as red light, green light, or blue light) to determine the redshift, and hence, through Hubble's law, the distance, of the observed object.
Photometric standard stars Photometric standard stars are a series of stars that have had their light output in various passbands of photometric system, measured very carefully. Other objects can be observed using CCD cameras or photoelectric photometers connected to a telescope, and the flux, or amount of light received, can be compared to a photometric standard star to determine the exact brightness, or stellar magnitude, of the object.
Photometric system In astronomy, a Photometric system is a set of discrete passbands (of filters), with a known sensitivity to incident radiation. The sensitivity usually depends on the optical system, detectors and filters used.
Photometry (astronomy) Photometry is a technique of astronomy concerned with measuring the flux, or intensity of an astronomical object's electromagnetic radiation. Usually, photometry refers to measurement over large wavelength bands of radiation; but, when not only the amount of radiation but its spectral distribution are measured the term spectrophotometry is used.
Photometry (optics) Photometry is the science of measurement of light, in terms of its perceived brightness to the human eye. It is distinct from radiometry, which is the science of measurement of light in terms of absolute power.
Photomicroscopy Photomicroscopy,also known as "Photomicrography", is the combined art of photography and microscopy and its name is a portmanteau of these two words. Photomicroscopy is usually performed simply by hooking up a regular camera to a microscope, thereby enabling the user to take photographs at reasonably high magnification Botresearch.
Photomixing Mixing of optical signals (photomixing also heterodyne generation) – radiation of two lasers with close frequencies or ultrashort optical pulses – can effectively stimulate generation of radiation with much longer wavelength (lower frequency) (e.g.
Photomontage Photomontage is the process (and result) of making a composite picture by cutting and joining a number of photographs. The composite picture is sometimes photographed so that the final image is converted back into a photographic print.
Photomultiplier Photomultiplier tubes (photomultipliers or PMTs for short) are extremely sensitive detectors of light in the ultraviolet, visible and near infrared. These detectors multiply the signal produced by incident light by as much as 108, from which single photons can be resolved.
Photon (TV series) Photon was a live action series based on the infrared tag game popular in the 1980s. The series took place on Earth and in space on various worlds and involved a young human teen named Christopher Jarvis who is a champion player of Photon.
Photon bunching In physics, photon bunching refers to the statistical tendency for photons to arrive simultaneously at a detector. This disturbs our understanding of classical particles, which tells us that non-interacting particles should know nothing about each other, and so should arrive independently of one another.
Photon diffusion Photon diffusion refers to a situation where photons travel through a material with a high optical depth and very short mean free path. Their behavior is then dominated by scattering and the path of any given photon is effectively a random walk.
Photon dynamics in the double-slit experiment The Dynamics of photons in the double-slit experiment describes the relationship between classical electromagnetic waves and photons, the quantum counterpart of classical electromagnetic waves, in the context of the double-slit experiment. The dynamics of a photon can be completely described by the classical Maxwell's equations with only a reinterpretation of the classical field as a probability amplitude for the photon.
Photon entanglement This brief explanation of photon entanglement is a supplement to the article Bohr-Einstein debates and is designed to help clarify the discussion of the Einstein-Podolsky-Rosen argument in quantum theory which takes place in that article.
Photon epoch In physical cosmology, the photon epoch was an era in which photons dominated the energy of the Universe. The epoch started after the lepton epoch, about 180 seconds after the Big Bang, and ended 300,000 years after the Big Bang when the Universe became transparent and the cosmic microwave radiation was created.
Photon gas In physics, a photon gas is a gas-like collection of photons, which has many of the same properties of a conventional gas like hydrogen or neon - including pressure, temperature, and entropy. The most common example of a photon gas in equilibrium is black body radiation.
Photon induced electric field poling In physics, photon induced electric field poling is a phenomenon whereby a pattern of local electric field orientations can be encoded in a suitable ferroelectric material, such as perovskite. The resulting encoded material is conceptually similar to the pattern of magnetic field orientations within the magnetic domains of a ferromagnet, and thus may be considered as a possible technology for computer storage media.
Photon mapping In computer graphics, photon mapping is a global illumination algorithm developed by Henrik Wann Jensen that solves the rendering equation. Rays from the light source and rays from the camera are traced independently until some termination criterion is met, then they are connected in a second step to produce a luminance value.
Photon noise In physics, the number of photons collected by an instrument which are emitted from any incoherent source are distributed according to a Poisson distribution, as long as the average intensity is constant over the bandwidth of the instrument. This is because the photons are discrete and the probability of one photon's arrival is independent of any other photon's arrival.
Photon polarization Photon polarization is the quantum mechanical description of the classical polarized sinusoidal plane electromagnetic wave. Individual photons can have elliptical polarization, circular polarization, or linear polarization.
Photon soup Photon soup is a project that aims to render an image by simulating the motion of all photons in a room. The original simulation in 1991, programmed in C by Richard Keene, took 100 Sun 1 computers operating at 1 MHz a month to render a single image.
Photon sphere A photon sphere is a spherical region of space surrounding extremely massive objects such as black holes. At a particular distance, the gravitational force is strong enough that photons approaching along tangents to the sphere will become trapped in an unstable orbit.
Photon: The Ultimate Game on Planet Earth Photon was the name of the first commercial lasertag arenas. The company also came out with a home lasertag game, and there were various media tie-ins; a TV show also called Photon and a series of novels by Peter David.
Photonic crystal Photonic crystals are periodic optical (nano)structures that are designed to affect the motion of photons in a similar way that periodicity of a semiconductor crystal affects the motion of electrons. Photonic crystals occur in nature and in various forms have been studied by science for the last 100 years.
Photonic integrated circuit A Photonic Integrated Circuit (PIC) is a device that integrates multiple photonic functions and as such is analogous to an Electronic Integrated Circuit. However the major difference between the two being that a photonic integrated circuit provides functionality for information signals imposed on optical wavelengths typically in the Visible spectrum or near infrared 850nm-1650nm.
Photonic-crystal fiber Photonic-crystal fiber (PCF), also spelled fibre, is a new class of optical fiber based on the properties of photonic crystals. Because of its ability to confine light in hollow cores or with confinement characteristics not possible in conventional optical fiber, PCF is now finding applications in fiber-optic communications, fiber lasers, nonlinear devices, high-power transmission, highly sensitive gas sensors, and other areas.

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