Spotlight operator
The Spotlight operator or Followspot Operator, is a theatrical technician who operates a specialized stage lighting instrument known as a followspot. A followspot is any lighting instrument manually controlled by an operator during a performance. A followspot will be a dedicated, large lighting instrument designed to pan, change size, beam width, color by hand. Choppers – Cuts or shutters the top and bottom part of the beam. Douser – Controls intensity. Iris – Controls beam size. Trombone – Controls focal length. Color Frames – Changes the color of the light. May known as a boomerang and/or a color magazine. Color magazines contain the color gels. Stage lighting Stage lighting instrument Light board operator Deck Electrician Super Trouper
Autofocus
An autofocus optical system uses a sensor, a control system and a motor to focus on an automatically or manually selected point or area. An electronic rangefinder has a display instead of the motor. Autofocus methods are distinguished by their type as being either active, passive or hybrid variants. Autofocus systems rely on one or more sensors to determine correct focus; some AF systems rely on a single sensor. Most modern SLR cameras use through-the-lens optical sensors, with a separate sensor array providing light metering, although the latter can be programmed to prioritize its metering to the same area as one or more of the AF sensors. Through-the-lens optical autofocusing is now speedier and more precise than can be achieved manually with an ordinary viewfinder, although more precise manual focus can be achieved with special accessories such as focusing magnifiers. Autofocus accuracy within 1/3 of the depth of field at the widest aperture of the lens is common in professional AF SLR cameras.
Most multi-sensor AF cameras allow manual selection of the active sensor, many offer automatic selection of the sensor using algorithms which attempt to discern the location of the subject. Some AF cameras are able to detect whether the subject is moving towards or away from the camera, including speed and acceleration data, keep focus on the subject — a function used in sports and other action photography; the data collected from AF sensors is used to control an electromechanical system that adjusts the focus of the optical system. A variation of autofocus is an electronic rangefinder, a system in which focus data are provided to the operator, but adjustment of the optical system is still performed manually; the speed of the AF system is dependent on the widest aperture offered by the lens. F-stops of around f/2 to f/2.8 are considered optimal in terms of focusing speed and accuracy. Faster lenses than this have low depth of field, meaning that it takes longer to achieve correct focus, despite the increased amount of light.
Most consumer camera systems will only autofocus reliably with lenses that have a widest aperture of at least f/5.6, while professional models can cope with lenses that have a widest aperture of f/8, useful for lenses used in conjunction with teleconverters. Between 1960 and 1973, Leitz patented an array of corresponding sensor technologies. At photokina 1976, Leica had presented a camera based on their previous development, named Correfot, in 1978 they displayed an SLR camera with operational autofocus; the first mass-produced autofocus camera was the Konica C35 AF, a simple point and shoot model released in 1977. The Polaroid SX-70 Sonar OneStep was the first autofocus single-lens reflex camera, released in 1978; the Pentax ME-F, which used focus sensors in the camera body coupled with a motorized lens, became the first autofocus 35 mm SLR in 1981. In 1983 Nikon released the F3AF, their first autofocus camera, based on a similar concept to the ME-F; the Minolta 7000, released in 1985, was the first SLR with an integrated autofocus system, meaning both the AF sensors and the drive motor were housed in the camera body, as well as an integrated film advance winder —, to become the standard configuration for SLR cameras from this manufacturer, Nikon abandoned their F3AF system and integrated the autofocus-motor and sensors in the body.
Canon, elected to develop their EOS system with motorised lenses instead. In 1992, Nikon changed back to lens integrated motors with their AF-S range of lenses. Active AF systems measure distance to the subject independently of the optical system, subsequently adjust the optical system for correct focus. There are various ways including ultrasonic sound waves and infrared light. In the first case, sound waves are emitted from the camera, by measuring the delay in their reflection, distance to the subject is calculated. Polaroid cameras including the Spectra and SX-70 were known for applying this system. In the latter case, infrared light is used to triangulate the distance to the subject. Compact cameras including the Nikon 35TiQD and 28TiQD, the Canon AF35M, the Contax T2 and T3, as well as early video cameras, used this system. A newer approach included in some consumer electronic devices, like mobile phones, is based on the time-of-flight principle, which involves shining a laser or LED light to the subject and calculating the distance based on the time it takes for the light to travel to the subject and back.
This technique is sometimes called laser autofocus, is present in many mobile phone models from several vendors. An exception to the two-step approach is the mechanical autofocus provided in some enlargers, which adjust the lens directly. Passive AF systems determine correct focus by performing passive analysis of the image, entering the optical system, they do not direct any energy, such as ultrasonic sound or infrared light waves, toward the subject. Passive autofocusing can be achieved by contrast measurement. Phase detection is achieved by comparing them. Through-the-lens secondary image registration (TTL
Odd-eyed cat
An odd-eyed cat is a cat with one blue eye and one eye either green, yellow, or brown. This is a feline form of complete heterochromia, a condition that occurs in some other animals, including humans; the condition most affects white-colored cats, but may be found in a cat of any color, provided that it possesses the white spotting gene. The odd-eyed coloring is caused when either the epistatic white gene or the white spotting gene prevents melanin granules from reaching one eye during development, resulting in a cat with one blue eye and one green, yellow, or brown eye; the condition only occurs in cats that lack both the dominant white and the white spotting gene. As with some other newborn mammals, all cats are blue-eyed as kittens, may change as the newborn ages; the differences in an odd-eyed kitten's eye color might not be noticeable, save upon close inspection. Odd-eyed kittens have a different shade of blue in each eye; the color of the odd eye changes over a period of months–for example, from blue to green to yellow or from green to blue to yellow–until it reaches its final, adult color.
Odd-eyed cats are popular within several breeds, including Turkish Van, Turkish Angora, Persian, Oriental Shorthair, Japanese Bobtail and Khao Manee. In 1817, the government of Turkey, in conjunction with the Ankara Zoo, began a meticulous breeding program to preserve and protect pure white Turkish Angora cats with blue and amber eyes, a program that continues today, as they are considered a national treasure; the zoo prized the odd-eyed Angoras who had one blue eye and one amber eye, as the Turkish folklore suggests that "the eyes must be as green as the lake and as blue as the sky." The mascot of the 2010 FIBA World Championship, hosted by Turkey, was an anthropomorphized odd-eyed Van Cat named "Bascat". Muhammad's pet Angora, was reputed to be an odd-eyed cat. In the Japanese Bobtail, odd-eyed cats are most found in calico individuals. There is a common misconception; this is not true, as about 60%–70% of odd-eyed cats can hear. About 10%–20% of normal-eyed cats are born deaf or become deaf as part of the feline aging process.
White cats with one or two blue eyes do, have a higher incidence of genetic deafness, with the white gene causing the degeneration of the cochlea, beginning a few days after birth. If a white kitten has any speck of another color, the frequency of deafness is diminished if the speck of coloration fades as the cat becomes more mature. In flash photographs, odd-eyed cats show a red-eye effect in the blue eye, but not in the other eye; this is due to the combined effect of the presence of a tapetum lucidum in both eyes and the absence of melanin in the blue eye. The tapetum lucidum produces eyeshine in both eyes, but in the non-blue eye a layer of melanin over the tapetum lucidum selectively removes some colors of light
Photography
Photography is the art and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed in many fields of science and business, as well as its more direct uses for art and video production, recreational purposes and mass communication. A lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, electronically processed and stored in a digital image file for subsequent display or processing; the result with photographic emulsion is an invisible latent image, chemically "developed" into a visible image, either negative or positive depending on the purpose of the photographic material and the method of processing. A negative image on film is traditionally used to photographically create a positive image on a paper base, known as a print, either by using an enlarger or by contact printing.
The word "photography" was created from the Greek roots φωτός, genitive of φῶς, "light" and γραφή "representation by means of lines" or "drawing", together meaning "drawing with light". Several people may have coined the same new term from these roots independently. Hercules Florence, a French painter and inventor living in Campinas, used the French form of the word, photographie, in private notes which a Brazilian historian believes were written in 1834; this claim is reported but has never been independently confirmed as beyond reasonable doubt. The German newspaper Vossische Zeitung of 25 February 1839 contained an article entitled Photographie, discussing several priority claims – Henry Fox Talbot's – regarding Daguerre's claim of invention; the article is the earliest known occurrence of the word in public print. It was signed "J. M.", believed to have been Berlin astronomer Johann von Maedler. The inventors Nicéphore Niépce, Henry Fox Talbot and Louis Daguerre seem not to have known or used the word "photography", but referred to their processes as "Heliography", "Photogenic Drawing"/"Talbotype"/"Calotype" and "Daguerreotype".
Photography is the result of combining several technical discoveries, relating to seeing an image and capturing the image. The discovery of the camera obscura that provides an image of a scene dates back to ancient China. Greek mathematicians Aristotle and Euclid independently described a pinhole camera in the 5th and 4th centuries BCE. In the 6th century CE, Byzantine mathematician Anthemius of Tralles used a type of camera obscura in his experiments; the Arab physicist Ibn al-Haytham invented a camera obscura and pinhole camera. Leonardo da Vinci mentions natural camera obscura that are formed by dark caves on the edge of a sunlit valley. A hole in the cave wall will act as a pinhole camera and project a laterally reversed, upside down image on a piece of paper. Renaissance painters used the camera obscura which, in fact, gives the optical rendering in color that dominates Western Art, it is a box with a hole in it which allows light to go through and create an image onto the piece of paper.
The birth of photography was concerned with inventing means to capture and keep the image produced by the camera obscura. Albertus Magnus discovered silver nitrate, Georg Fabricius discovered silver chloride, the techniques described in Ibn al-Haytham's Book of Optics are capable of producing primitive photographs using medieval materials. Daniele Barbaro described a diaphragm in 1566. Wilhelm Homberg described how light darkened some chemicals in 1694; the fiction book Giphantie, published in 1760, by French author Tiphaigne de la Roche, described what can be interpreted as photography. Around the year 1800, British inventor Thomas Wedgwood made the first known attempt to capture the image in a camera obscura by means of a light-sensitive substance, he used paper or white leather treated with silver nitrate. Although he succeeded in capturing the shadows of objects placed on the surface in direct sunlight, made shadow copies of paintings on glass, it was reported in 1802 that "the images formed by means of a camera obscura have been found too faint to produce, in any moderate time, an effect upon the nitrate of silver."
The shadow images darkened all over. The first permanent photoetching was an image produced in 1822 by the French inventor Nicéphore Niépce, but it was destroyed in a attempt to make prints from it. Niépce was successful again in 1825. In 1826 or 1827, he made the View from the Window at Le Gras, the earliest surviving photograph from nature; because Niépce's camera photographs required an long exposure, he sought to improve his bitumen process or replace it with one, more practical. In partnership with Louis Daguerre, he worked out post-exposure processing methods that produced visually superior results and replaced the bitumen with a more light-sensitive resin, but hours of exposure in the camera were still required. With an eye to eventual commercial exploitation, the partners opted for total secrecy. Niépce died in 1833 and Daguerre redirected the experiments toward the light-sensitive silver halides, which Niépce had abandoned many years earlier because of his inability to make the images he captured with them light-fast and permanent.
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Raster graphics editor
A raster graphics editor is a computer program that allows users to create and edit images interactively on the computer screen and save them in one of many "bitmap" or "raster" formats such as JPEG, PNG, GIF. Vector graphics editors are contrasted with raster graphics editors, yet their capabilities complement each other; the technical difference between vector and raster editors stem from the difference between vector and raster images. Vector graphics are created mathematically; each element is manipulated numerically. Raster images include digital photos. A raster image is made up of rows and columns of dots, called pixels, is more photo-realistic; this is the standard form for digital cameras. The image is represented pixel like a microscopic jigsaw puzzle. Vector editors tend to be better suited for graphic design, page layout, logos, sharp-edged artistic illustrations, e.g. cartoons, clip art, complex geometric patterns, technical illustrations and flowcharting. Advanced raster editors, like GIMP and Adobe Photoshop, use vector methods for general layout and elements such as text, but are equipped to deal with raster images down to the pixel and have special capabilities in doing so, such as brightness/contrast, adding "lighting" to a raster image or photograph.
Select a region for editing Draw lines with simulated brushes of different color, size and pressure Fill a region with a single color, gradient of colors, or a texture Select a color using different color models, e.g. RGB, HSV, or by using a color dropper Edit and convert between various color models. Add typed letters in various font styles Remove imperfections from photo images Composite editing using layers Apply filters for effects including sharpening and blurring Convert between various image file formats Comparison of raster graphics editors Vector graphics editor Texture map Text editor 3D modelling software Media related to Bitmap graphics editors at Wikimedia Commons
Retinal pigment epithelium
The pigmented layer of retina or retinal pigment epithelium is the pigmented cell layer just outside the neurosensory retina that nourishes retinal visual cells, is attached to the underlying choroid and overlying retinal visual cells. The RPE was known in the 18th and 19th centuries as the pigmentum nigrum, referring to the observation that the RPE is dark; the RPE is composed of a single layer of hexagonal cells that are densely packed with pigment granules. When viewed from the outer surface, these cells are hexagonal in shape; when seen in section, each cell consists of an outer non-pigmented part containing a large oval nucleus and an inner pigmented portion which extends as a series of straight thread-like processes between the rods, this being the case when the eye is exposed to light. The RPE has several functions, light absorption, epithelial transport, spatial ion buffering, visual cycle, phagocytosis and immune modulation. Light absorption: RPE are responsible for absorbing scattered light.
This role is important for two main reasons, first, to improve the quality of the optical system, light is radiation, it is concentrated by a lens onto the cells of the macula, resulting in a strong concentration of photo-oxidative energy. Melanosomes thus diminish the photo-oxidative stress; the high perfusion of retina brings a high oxygen tension environment. The combination of light and oxygen brings oxidative stress, RPE has many mechanisms to cope with it. Epithelial transport: As mentioned above, RPE compose the blood–retinal barrier, the epithelia has tight junctions between the lateral surfaces and implies an isolation of the inner retina from the systemic influences; this is important for the immune privilege of eyes, a selective transport of substances for a controlled environment. RPE control ion homeostasis and eliminate water and metabolites. Spatial buffering of ions: Changes in the subretinal space are fast and require a capacitative compensation by RPE many cells are involved in transduction of light and if they are not compensated for, they are no longer excitable and proper transduction would not be possible.
The normal transepithelial transport of ions would be too slow to compensate enough for these changes, there are many underlying mechanisms based on the activity of voltage-dependent ion channels add to the basic transepithelial transport of ions. Visual cycle: The visual cycle fulfills an essential task of maintaining visual function and needs therefore to be adapted to different visual needs such as vision in darkness or lightness. For this, functional aspects come into play: the storage of retinal and the adaption of the reaction speed. Vision at low light intensities requires a lower turn-over rate of the visual cycle whereas during light the turn-over rate is much higher. In the transition from darkness to light large amount of 11-cis retinal is required; this comes not directly from the visual cycle but from several retinal pools of retinal binding proteins which are connected to each other by the transportation and reaction steps of the visual cycle. Phagocytosis of photoreceptor outer segment membranes: POS are exposed to constant photo-oxidative stress, they go through constant destruction by it.
They are renewed by shedding their end, which RPE phagocytose and digest. Secretion: The RPE is an epithelium which interacts with photoreceptors on one side but must be able to interact with cells on the blood side of the epithelium, such as endothelial cells or cells of the immune system. In order to communicate with the neighboring tissues the RPE is able to secrete a large variety of factors and signaling molecules, it secretes ATP, fas-ligand, fibroblast growth factors, transforming growth factor-β, insulin-like growth factor-1, ciliary neurotrophic factor, platelet-derived growth factor, vascular endothelial growth factor, lens epithelium-derived growth factor, members of the interleukin family, tissue inhibitor of matrix metalloproteinase and pigment epithelium-derived factor. Many of these signaling molecules have important physiopathologic roles. Immune privilege of the eye: The inner eye represents an immune privileged space, disconnected from the immune system of the blood stream.
The immune privilege is supported by the RPE in two ways. First, it represents a mechanical and tight barrier which separates the inner space of the eye from the blood stream. Second, the RPE is able to communicate with the immune system in order to silence immune reaction in the healthy eye or, on the other hand, to activate the immune system in the case of disease. In the eyes of albinos, the cells of this layer contain no pigment. Dysfunction of the RPE is found in age-related macular degeneration and retinitis pigmentosa. RPE are involved in diabetic retinopathy. Gardner syndrome is characterized by FAP, osseous and soft tissue tumors, retinal pigment epithelium hypertrophy and impacted teeth. Bruch's membrane Drusen Macula of retina Fovea centralis Fundus This article incorporates text in the public domain from page 1016 of the 20th edition of Gray's Anatomy pigment+epithelium+of+eye at the US National Library of Medicine Medical Subject Headings Histology image: 07902loa – Histology Learning System at Boston University Histology at KUMC eye_ea
