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Orthochromatic
In chemistry, orthochromasia is the property of a dye or stain to not change color on binding to a target, as opposed to ''metachromatic'' stains, which do change color. The word is derived from the Greek '' orthos'' (correct, upright), and chromatic (color). Toluidine blue is an example of a partially orthochromatic dye, as it stains nucleic acids by its orthochromatic color (blue), but stains mast cell granules in its metachromatic color (red). In spectral terms, orthochromasia refers to maintaining the position of spectral peaks, while metachromasia refers to a shift in wavelength, becoming either shorter or longer. In photography, an orthochromatic light spectrum is one devoid of red light. Orthochromatic photography Orthochromatic photography refers to a photographic emulsion that is sensitive to blue and green light but not red light. This type of emulsion was a significant advancement in early photography, as it allowed for the production of images with more acc ...
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Panchromatic
A panchromatic emulsion is a type of photographic emulsion that is sensitive to all wavelengths of visible light, and produces a monochrome photograph—typically black and white. Most modern commercially available film is panchromatic, and the technology is usually contrasted with earlier methods that cannot register all wavelengths, especially orthochromatic film. In digital imaging, a panchromatic sensor is an image sensor or array of sensors that combine the visible spectrum with non-visible wavelengths, such as ultraviolet or infrared. Images produced are also black and white, and the system is used for its ability to produce higher resolution images than standard digital sensors. Description A panchromatic emulsion renders a realistic reproduction of a scene as it appears to the human eye, although with no colors. Almost all modern photographic film is panchromatic. Some older types of film were orthochromatic and were not sensitive to certain wavelengths of light. As ...
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Panchromatic Film
A panchromatic emulsion is a type of photographic emulsion that is sensitive to all wavelengths of visible light, and produces a monochrome photograph—typically black and white. Most modern commercially available film is panchromatic, and the technology is usually contrasted with earlier methods that cannot register all wavelengths, especially orthochromatic film. In digital imaging, a panchromatic sensor is an image sensor or array of sensors that combine the visible spectrum with non-visible wavelengths, such as ultraviolet or infrared. Images produced are also black and white, and the system is used for its ability to produce higher resolution images than standard digital sensors. Description A panchromatic emulsion renders a realistic reproduction of a scene as it appears to the human eye, although with no colors. Almost all modern photographic film is panchromatic. Some older types of film were orthochromatic and were not sensitive to certain wavelengths of light. A ...
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Photographic Filter
In photography and cinematography, a filter is a camera accessory consisting of an optical filter that can be inserted into the optical path. The filter can be of a square or oblong shape and mounted in a holder accessory, or, more commonly, a glass or plastic disk in a metal or plastic ring frame, which can be screwed into the front of or clipped onto the camera lens. Filters modify the images recorded. Sometimes they are used to make only subtle changes to images; other times the image would simply not be possible without them. In monochrome photography, coloured filters affect the relative brightness of different colours; red lipstick may be rendered as anything from almost white to almost black with different filters. Others change the colour balance of images, so that photographs under incandescent lighting show colours as they are perceived, rather than with a reddish tinge. There are filters that distort the image in a desired way, diffusing an otherwise sharp image, add ...
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Royal Air Force Roundels
The air forces of the United Kingdom – the Royal Navy's Fleet Air Arm, the Army's Army Air Corps and the Royal Air Force use a roundel, a circular identification mark, painted on aircraft to identify them to other aircraft and ground forces. In one form or another, it has been used on British military aircraft from 1915 to the present. Background When the First World War started in 1914 it was the habit of ground troops to fire on all aircraft, friend or foe, so that the need for some form of identification mark became evident.Robertson 1967, p 89 At first the Union Flag was painted under the wings and on the sides of the fuselage. It soon became obvious that at a distance the St George's Cross of the Union Flag was likely to be confused with the Iron Cross that was already being used to identify German aircraft. After the use of a Union Flag inside a shield was tried it was decided to follow the lead of the French who used a tricolour cockade (a roundel of red and whit ...
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Cyan
Cyan () is the color between blue and green on the visible spectrum of light. It is evoked by light with a predominant wavelength between 500 and 520 nm, between the wavelengths of green and blue. In the subtractive color system, or CMYK color model, which can be overlaid to produce all colors in paint and color printing, cyan is one of the primary colors, along with magenta and yellow. In the additive color system, or RGB color model, used to create all the colors on a computer or television display, cyan is made by mixing equal amounts of green and blue light. Cyan is the complement of red; it can be made by the removal of red from white. Mixing red light and cyan light at the right intensity will make white light. It is commonly seen on a bright, sunny day in the sky. Shades and variations Different shades of cyan can vary in terms of hue, chroma (also known as saturation, intensity, or colorfulness), or lightness (or value, tone, or brightness), or any combinat ...
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Erythrosine
Erythrosine, also known as E127 and Red No. 3, is an organoiodine compound, specifically a derivative of fluorone. It is a red-pink dye used for food coloring, cosmetics, hair coloring, pet products, and diverse industrial colorings. It is the disodium salt of 2,4,5,7-tetraiodofluorescein. History The colorant was discovered by the Swiss chemist Karl Kussmaul at the University of Basel in 1876 and soon commercialized by the local Bindschedler & Busch company for dyeing wool and silk. Its use as a food dye was legalized in the US by the Pure Food and Drug Act of 1906. By early 1920s, it was produced mainly for the food industry, with made in America in 1924, rising to in 1938 and approximately 50 tons in 1967. Production Erythrosine is synthesized from phenol and phthalic anhydride, which are processed into fluorescein. Fluorescein then undergoes iodination, producing the bright red dye. Uses It is used as a food coloring, printing ink, biological stain, dental plaque disc ...
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Hermann Wilhelm Vogel
Hermann Wilhelm Vogel (26 March 1834 – 17 December 1898) was a German photochemist and photographer who discovered dye sensitization, which is of great importance to photography. Academic career After finishing school in Frankfurt (Oder), he studied at the Royal Industrial Institute of Berlin, earning his Ph.D. with Karl Friedrich August Rammelsberg in 1863. Vogel's thesis, which was published in ''Poggendorffs Annalen'' , had the title: ''Über das Verhalten des Chlorsilbers, Bromsilbers und Iodsilbers im Licht und die Theorie der Photographie'' (Reactions of Silver Chloride, Silver Bromide and Silver Iodide with Light and the Theory of Photography). This marked the beginning of his research into the photographic process. From 1860 until 1865, he was an assistant in the mineralogical museum of the University of Berlin. From 1864 he was a professor at the Technische Hochschule in Charlottenburg (today Technische Universität Berlin), where he introduced photography as a f ...
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ColorChecker
File:CIE1931xy_ColorChecker_SMIL.svg, 300px, Nominal chromaticities of ColorChecker patches in the CIE 1931 xy chromaticity diagram (in thSVG version hover over a color swatch to highlight it; click it to select and deselect it) defaul The ColorChecker color chart, Color Rendition Chart (often referred to by its original name, the Macbeth ColorChecker or simply Macbeth chart) is a color calibration target consisting of a cardboard-framed arrangement of 24 squares of painted samples. The ColorChecker was introduced in a 1976 paper by McCamy, Marcus, and Davidson in the '' Journal of Applied Photographic Engineering''.C. S. McCamy, H. Marcus, and J. G. Davidson (1976)"A Color-Rendition Chart" ''Journal of Applied Photographic Engineering'' 2(3). 95–99. The chart’s color patches have spectral reflectances intended to mimic those of natural objects such as human skin, foliage, and flowers, to have consistent color appearance under a variety of lighting conditions, especially a ...
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Safelight
A safelight is a light source suitable for use in a photographic darkroom. It provides illumination only from parts of the visible spectrum to which the photographic material in use is nearly, or completely insensitive. Design A safelight usually consists of an ordinary light bulb in a housing closed off by a coloured filter, but sometimes a special light bulb or fluorescent tube with suitable filter material or phosphor (in fluorescent tubes) coated directly on the glass is used in an ordinary fixture. More recently LEDs, which have a relatively narrow spectral bandwidth, are becoming more popular. Differently sensitised materials require different safelights. In traditional black-and-white photographic printing, photographic papers normally are handled under an amber or red safelight, as such papers typically are sensitive only to blue and green light. Orthochromatic papers and films are also sensitive to yellow light and must be used only with a deep red safelight, not with ...
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Josef Maria Eder
Josef Maria Eder (16 March 1855 – 18 October 1944) was an Austrian chemist who specialized in the chemistry of photography, and who wrote a comprehensive early history of the technical development of chemical photography. Life and work Eder was born in Krems an der Donau in 1855. He studied chemistry, physics and mathematics at the Vienna University of Technology and at the University of Vienna. In 1876, he received his PhD and in 1879, after his habilitation, became lecturer at the Vienna University of Technology. Eder's research then focused on the chemistry of photography. After spending some time at the Staatliche Gewerbeschule Vienna, he became lecturer at the Höhere Gewerbeschule Vienna. This change improved his capacity to undertake research. In the following years, Eder developed a sensitized gelatin silver process. Orthochromatic photographic plates, in combination with a color filter counter-acting the plates' inhomogeneous sensitivity to light of different wavelength ...
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