In photography and image processing, color balance is the global adjustment of the intensities of the colors. An important goal of this adjustment is to specific colors – particularly neutral colors – correctly. Hence, the method is sometimes called gray balance, neutral balance. Color balance changes the mixture of colors in an image and is used for color correction. Generalized versions of color balance are used to correct colors other than neutrals or to change them for effect. Image data acquired by sensors – either film or electronic image sensors – must be transformed from the values to new values that are appropriate for color reproduction or display. In film photography, color balance is achieved by using color correction filters over the lights or on the camera lens. It is particularly important that neutral colors in a scene appear neutral in the reproduction, most digital cameras have means to select color correction based on the type of scene lighting, using either manual lighting selection, automatic white balance, or custom white balance.
The algorithms for these processes perform generalized chromatic adaptation, many methods exist for color balancing. Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting, another option on some cameras is a button which one may press when the camera is pointed at a gray card or other neutral colored object. This captures an image of the ambient light, which enables a digital camera to set the color balance for that light. There is a literature on how one might estimate the ambient lighting from the camera data. A variety of algorithms have been proposed, and the quality of these has been debated, a few examples and examination of the references therein will lead the reader to many others. Examples are Retinex, a neural network or a Bayesian method. Color balancing an image not only the neutrals, but other colors as well. An image that is not color balanced is said to have a color cast, Color balancing may be thought in terms of removing this color cast.
Color balance is related to color constancy. Algorithms and techniques used to color constancy are frequently used for color balancing
In photography, the metering mode refers to the way in which a camera determines the exposure. Cameras generally allow the user to select between spot, center-weighted average, or multi-zone metering modes, various metering modes are provided to allow the user to select the most appropriate one for use in a variety of lighting conditions. With spot metering, the camera will only measure a small area of the scene. This will by default be the centre of the scene. The user can select a different off-centre spot, or to recompose by moving the camera after metering. The first spot meter was built by Arthur James Dalladay, editor of The British Journal of Photography in about 1935, a few models support a Multi-Spot mode which allows multiple spot meter readings to be taken of a scene that are averaged. Some cameras, the OM-4 and T90 included, support metering of highlight, spot metering is very accurate and is not influenced by other areas in the frame. It is commonly used to very high contrast scenes.
The area around the back and hairline will become over-exposed, spot metering is a method upon which the Zone System depends. In many cases the camera will over or underexpose, when using the spot mode, modern cameras tend to find the correct exposure precisely. In complex light situations though, professional photographers tend to switch to manual mode, another example of spot metering usage would be when photographing the moon. Due to the dark nature of the scene, other metering methods tend to overexpose the moon. Spot metering will allow for more detail to be out in the moon while underexposing the rest of the scene. More commonly, spot metering is used in photography, where the brightly lit actors stand before a dark or even black curtain or scrim. Spot metering only considers the actors in this case, while ignoring the overall darkness of the scene, in this system, the meter concentrates between 60 to 80 percent of the sensitivity towards the central part of the viewfinder. The balance is feathered out towards the edges, some cameras will allow the user to adjust the weight/balance of the central portion to the peripheral one.
When moving the point off center the camera will proceed as above. Although promoted as a feature, center-weighted metering was originally a consequence of the meter cell reading from the screen of SLR cameras
It is headquartered in Ōta, Japan. Canon has a listing on the Tokyo Stock Exchange and is a constituent of the TOPIX index. It has a listing on the New York Stock Exchange. At the beginning of 2015, Canon was the tenth largest public company in Japan when measured by market capitalization, the company was originally named Seikikōgaku kenkyūsho. In 1934 it produced the Kwanon, a prototype for Japan’s first-ever 35 mm camera with a plane based shutter. In 1947 the company name was changed to Canon Camera Co. Inc. shortened to Canon Inc. in 1969, the name Canon comes from Buddhist bodhisattva Guan Yin, previously transliterated as Kuanyin, Kwannon, or Kwanon in English. The origins of Canon date back to the founding of Precision Optical Instruments Laboratory in Japan in 1937 by Takeshi Mitarai, Goro Yoshida, Saburo Uchida and Takeo Maeda. During its early years the company did not have any facilities to produce its own optical glass, between 1933 and 1936 ‘The Kwanon’, a copy of the Leica design, Japan’s first 35 mm focal plane-shutter camera, was developed in prototype form.
In 1940 Canon developed Japans first indirect X-ray camera, Canon introduced a field zoom lens for television broadcasting in 1958 and in 1959 introduced the Reflex Zoom 8, the world’s first movie camera with a zoom lens, and the Canonflex. In 1961 Canon introduced the Rangefinder camera, Canon 7, in 1965 Canon introduced the Canon Pellix, a single lens reflex camera with a semi-transparent stationary mirror which enabled the taking of pictures through the mirror. In 1971 Canon introduced the F-1, a high-end SLR camera, in 1976 Canon launched the AE-1, the world’s first camera with an embedded micro-computer. In 1982 Wildlife as Canon Sees It print ads first appeared in National Geographic magazine, Canon introduced the world’s first Inkjet printer using bubble jet technology in 1985. Canon introduced Canon Electro-Optical System in 1987, named after the goddess of the dawn, EOS650 autofocus SLR camera is introduced. Also in 1987 the Canon Foundation was established, in 1988 Canon introduced Kyosei philosophy.
The EOS1 Flagship Professional SLR line was launched in 1989, in the same year the EOS RT, the worlds first AF SLR with a fixed, semi-transparent pellicle mirror, was unveiled. In 1992 Canon launched the EOS5, the camera with eye-controlled AF. In 1995 Canon introduced the first commercially available SLR lens with image stabilization. EOS-1N RS, the worlds fastest AF SLR camera with a shooting speed of 10 frame/s at the time
The f-number of an optical system such as a camera lens is the ratio of the systems focal length to the diameter of the entrance pupil. It is a number that is a quantitative measure of lens speed. It is known as the ratio, f-ratio, f-stop. The f-number is commonly indicated using a hooked f with the format f/N, the f-number N or f# is given by, N = f D where f is the focal length, and D is the diameter of the entrance pupil. It is customary to write f-numbers preceded by f/, which forms a mathematical expression of the pupil diameter in terms of f and N. Ignoring differences in light transmission efficiency, a lens with a greater f-number projects darker images, the brightness of the projected image relative to the brightness of the scene in the lenss field of view decreases with the square of the f-number. Doubling the f-number decreases the brightness by a factor of four. To maintain the same photographic exposure when doubling the f-number, the time would need to be four times as long. Most lenses have a diaphragm, which changes the size of the aperture stop.
The entrance pupil diameter is not necessarily equal to the aperture stop diameter, a 100 mm focal length f/4 lens has an entrance pupil diameter of 25 mm. A200 mm focal length f/4 lens has a pupil diameter of 50 mm. The 200 mm lenss entrance pupil has four times the area of the 100 mm lenss entrance pupil, a T-stop is an f-number adjusted to account for light transmission efficiency. The word stop is sometimes confusing due to its multiple meanings, a stop can be a physical object, an opaque part of an optical system that blocks certain rays. In photography, stops are a used to quantify ratios of light or exposure. The one-stop unit is known as the EV unit. On a camera, the setting is traditionally adjusted in discrete steps. Each stop is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop. This corresponds to a decrease of the pupil and aperture diameters by a factor of 1/2 or about 0.7071, each element in the sequence is one stop lower than the element to its left, and one stop higher than the element to its right
It is not used in JPEG2000, PNG, or GIF. This standard consists of the Exif image file specification and the Exif audio file specification, the Japan Electronic Industries Development Association produced the initial definition of Exif. Version 2.1 of the specification is dated 12 June 1998, JEITA established Exif version 2.2, dated 20 February 2002 and released in April 2002. Version 2.21 is dated 11 July 2003, but was released in September 2003 following the release of DCF2.0, the latest, version 2.3, released on 26 April 2010 and revised in May 2013, was jointly formulated by JEITA and CIPA. Exif is supported by almost all camera manufacturers, the metadata tags defined in the Exif standard cover a broad spectrum and time information. Digital cameras will record the current date and time and save this in the metadata, a thumbnail for previewing the picture on the cameras LCD screen, in file managers, or in photo manipulation software. The Exif tag structure is borrowed from TIFF files, on several image specific properties, there is a large overlap between the tags defined in the TIFF, Exif, TIFF/EP, and DCF standards.
For descriptive metadata, there is an overlap between Exif, IPTC Information Interchange Model and XMP info, which can be embedded in a JPEG file, the Metadata Working Group has guidelines on mapping tags between these standards. When Exif is employed for JPEG files, the Exif data are stored in one of JPEGs defined utility Application Segments, the APP1, when Exif is employed in TIFF files, the TIFF Private Tag 0x8769 defines a sub-Image File Directory that holds the Exif specified TIFF Tags. Formats specified in Exif standard are defined as structures that are based on Exif-JPEG. When these formats are used as Exif/DCF files together with the DCF specification, their scope shall cover devices, recording media, the Exif format has standard tags for location information. As of 2014 many cameras and most mobile phones have a built-in GPS receiver that stores the information in the Exif header when a picture is taken. Some other cameras have a separate GPS receiver that fits into the connector or hot shoe.
The process of adding information to a photograph is known as geotagging. Photo-sharing communities like Panoramio, locr or Flickr equally allow their users to upload geocoded pictures or to add geolocation information online, Exif data are embedded within the image file itself. While many recent image manipulation programs recognize and preserve Exif data when writing to a modified image, many image gallery programs recognise Exif data and optionally display it alongside the images. The Exif format has a number of drawbacks, mostly relating to its use of file structures. For this reason most image editors damage or remove the Exif metadata to some extent upon saving, the standard defines a MakerNote tag, which allows camera manufacturers to place any custom format metadata in the file
The focal length of an optical system is a measure of how strongly the system converges or diverges light. For an optical system in air, it is the distance over which initially collimated rays are brought to a focus. A system with a focal length has greater optical power than one with a long focal length. For a thin lens in air, the length is the distance from the center of the lens to the principal foci of the lens. For a converging lens, the length is positive, and is the distance at which a beam of collimated light will be focused to a single spot. For a diverging lens, the length is negative, and is the distance to the point from which a collimated beam appears to be diverging after passing through the lens. The focal length of a lens can be easily measured by using it to form an image of a distant light source on a screen. The lens is moved until an image is formed on the screen. In this case 1/u is negligible, and the length is given by f ≈ v. Back focal length or back focal distance is the distance from the vertex of the last optical surface of the system to the focal point.
For an optical system in air, the focal length gives the distance from the front. If the surrounding medium is not air, the distance is multiplied by the index of the medium. Some authors call these distances the front/rear focal lengths, distinguishing them from the front/rear focal distances, defined above. In general, the length or EFL is the value that describes the ability of the optical system to focus light. The other parameters are used in determining where an image will be formed for an object position. The quantity 1/f is known as the power of the lens. The corresponding front focal distance is, FFD = f, in the sign convention used here, the value of R1 will be positive if the first lens surface is convex, and negative if it is concave. The value of R2 is negative if the surface is convex
Film speed is the measure of a photographic films sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to measure the sensitivity of digital imaging systems, highly sensitive films are correspondingly termed fast films. In both digital and film photography, the reduction of exposure corresponding to use of higher sensitivities generally leads to reduced image quality, in short, the higher the sensitivity, the grainier the image will be. Ultimately sensitivity is limited by the efficiency of the film or sensor. The speed of the emulsion was expressed in degrees Warnerke corresponding with the last number visible on the plate after development. Each number represented an increase of 1/3 in speed, typical speeds were between 10° and 25° Warnerke at the time. The concept, was built upon in 1900 by Henry Chapman Jones in the development of his plate tester. In their system, speed numbers were inversely proportional to the exposure required, for example, an emulsion rated at 250 H&D would require ten times the exposure of an emulsion rated at 2500 H&D.
The methods to determine the sensitivity were modified in 1925, the H&D system was officially accepted as a standard in the former Soviet Union from 1928 until September 1951, when it was superseded by GOST 2817-50. The Scheinergrade system was devised by the German astronomer Julius Scheiner in 1894 originally as a method of comparing the speeds of plates used for astronomical photography, Scheiners system rated the speed of a plate by the least exposure to produce a visible darkening upon development. ≈2 The system was extended to cover larger ranges and some of its practical shortcomings were addressed by the Austrian scientist Josef Maria Eder. Scheiners system was abandoned in Germany, when the standardized DIN system was introduced in 1934. In various forms, it continued to be in use in other countries for some time. The DIN system, officially DIN standard 4512 by Deutsches Institut für Normung, was published in January 1934, International Congress of Photography held in Dresden from August 3 to 8,1931.
The DIN system was inspired by Scheiners system, but the sensitivities were represented as the base 10 logarithm of the sensitivity multiplied by 10, similar to decibels. Thus an increase of 20° represented an increase in sensitivity. ≈3 /10 As in the Scheiner system, speeds were expressed in degrees, originally the sensitivity was written as a fraction with tenths, where the resultant value 1.8 represented the relative base 10 logarithm of the speed. Tenths were abandoned with DIN4512, 1957-11, and the example above would be written as 18° DIN, the degree symbol was finally dropped with DIN4512, 1961-10
The amount of light that reaches the film or image sensor is proportional to the exposure time. 1/500th of a second will let half as much light in as 1/250th, the cameras shutter speed, the lenss aperture, and the scenes luminance together determine the amount of light that reaches the film or sensor. Exposure value is a quantity that accounts for the shutter speed and this will achieve a good exposure when all the details of the scene are legible on the photograph. Too much light let into the results in an overly pale image while too little light will result in an overly dark image. Multiple combinations of speed and f-number can give the same exposure value. According to exposure value formula, doubling the exposure time doubles the amount of light, for example, f/8 lets 4 times more light into the camera as f/16 does. In addition to its effect on exposure, the speed changes the way movement appears in photographs. Very short shutter speeds can be used to freeze fast-moving subjects, very long shutter speeds are used to intentionally blur a moving subject for effect.
Short exposure times are called fast, and long exposure times slow. Adjustments to the aperture need to be compensated by changes of the speed to keep the same exposure. The agreed standards for shutter speeds are, With this scale, camera shutters often include one or two other settings for making very long exposures, B keeps the shutter open as long as the shutter release is held. T keeps the open until the shutter release is pressed again. The ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of the slowest possible speed for a handheld camera. Through practice and special techniques such as bracing the camera, arms, or body to minimize movement, using a monopod or a tripod. If a shutter speed is too slow for hand holding, a support, usually a tripod. Image stabilization on digital cameras or lenses can often permit the use of shutter speeds 3–4 stops slower, Shutter priority refers to a shooting mode used in cameras.
It allows the photographer to choose a shutter speed setting and allow the camera to decide the correct aperture and this is sometimes referred to as Shutter Speed Priority Auto Exposure, or TV mode, S mode on Nikons and most other brands. Shutter speed is one of methods used to control the amount of light recorded by the cameras digital sensor or film
The indigo bunting is a small seed-eating bird in the family Cardinalidae or cardinal. It is migratory, ranging from southern Canada to northern Florida during the breeding season and it often migrates by night, using the stars to navigate. Its habitat is farmland, brush areas, and open woodland, the indigo bunting is closely related to the lazuli bunting and interbreeds with the species where their ranges overlap. The indigo bunting is a bird, with a length of 11. 5–13 cm. It displays sexual dimorphism in its coloration, the male is a vibrant blue in the summer, the male displays brightly colored plumage during the breeding season to attract a mate. Nest-building and incubation are done solely by the female, the diet of the indigo bunting consists primarily of insects during the summer months and seeds during the winter months. The indigo bunting is included in the family Cardinalidae, which is made up of birds found in North and South America. It was originally described as Tanagra cyanea by Linnaeus in his 18th-century work, Systema Naturae.
The current genus name, Passerina, is derived from the Latin term passer for true sparrows and similar birds, while the species name. The indigo bunting is closely related to the bunting and interbreeds with the species where their ranges overlap. They were declared to form a superspecies by the American Ornithologists Union in 1983, according to sequencing of the mitochondrial cytochrome-b gene of members of the genus Passerina, it was determined that the indigo bunting and lazuli bunting are not, in fact, sister taxa. The indigo bunting is the sister of two groups, a “blue” and a “painted” clade. This genetic study shows these species diverged between 4.1 and 7.3 million years ago and this timing, which is consistent with fossil evidence, coincides with a late-Miocene cooling, which caused the evolution of a variety of western grassland habitats. Evolving to reduce size may have allowed buntings to exploit grass seeds as a food source, the indigo bunting is a smallish songbird, around the size of a small sparrow.
It measures 11. 5–15 cm long, with a wingspan of 18–23 cm, body mass averages 14.5 g, with a reported range of 11. 2–21.4 g. During the breeding season, the male appears mostly a vibrant cerulean blue. The wings and tail are black with blue edges. In fall and winter plumage, the male has brown edges to the body and head feathers
A flash is a device used in photography producing a flash of artificial light at a color temperature of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene, other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs, modern cameras often activate flash units automatically. Flash units are built directly into a camera. Some cameras allow separate flash units to be mounted via an accessory mount bracket. In professional studio equipment, flashes may be large, standalone units, or studio strobes, studies of magnesium by Bunsen and Roscoe in 1859 showed that burning this metal produced a light with similar qualities to daylight. The potential application to photography inspired Edward Sonstadt to investigate methods of manufacturing magnesium so that it would burn reliably for this use and he applied for patents in 1862 and by 1864 had started the Manchester Magnesium Company with Edward Mellor.
It had the benefit of being a simpler and cheaper process than making round wire, mather was credited with the invention of a holder for the ribbon, which formed a lamp to burn it in. The packaging implies that the ribbon was not necessarily broken off before being ignited. An alternative to ribbon was flash powder, a mixture of powder and potassium chlorate, introduced by its German inventors Adolf Miethe. A measured amount was put into a pan or trough and ignited by hand, producing a brilliant flash of light, along with the smoke. This could be an activity, especially if the flash powder was damp. An electrically triggered flash lamp was invented by Joshua Lionel Cowen in 1899 and his patent describes a device for igniting photographers’ flash powder by using dry cell batteries to heat a wire fuse. Variations and alternatives were touted from time to time and a few found a measure of success in the marketplace, especially for amateur use. The use of powder in an open lamp was replaced by flashbulbs, magnesium filaments were contained in bulbs filled with oxygen gas.
Manufactured flashbulbs were first produced commercially in Germany in 1929, such a bulb could only be used once, and was too hot to handle immediately after use, but the confinement of what would otherwise have amounted to a small explosion was an important advance. A innovation was the coating of flashbulbs with a film to maintain bulb integrity in the event of the glass shattering during the flash
Canon EOS 7D
The Canon EOS 7D is a semi-professional cropped sensor digital single-lens reflex camera made by Canon. It was announced on 1 September 2009 with a retail price of US$1,699. The 7D remained in Canons model lineup without replacement for more than five years—the longest product cycle for any EOS digital camera. Its successor was the Canon EOS 7D Mark II, announced on 15 September 2014, center point is high precision, double cross-type at f/2. The AF system is a new design uses a translucent LCD display in the viewfinder. The camera uses TTL63 zone color sensitive metering system with four variations, e-TTL II flash metering is provided. The translucent LCD can display guide lines and the metering area circle. As with most other video-capable DSLRs, the Canon EOS 7D’s autofocusing function does not work while recording video, users can only trigger a contrast-detect AF cycle before recording process by hitting the AF button on the cameras rear panel. Users can manually focus the lens during a recording, the shutter is rated to 150,000 shots, and is capable of speeds up to 1/8000 sec, with a flash sync speed of 1/250 sec.
The 7D has roughly the same dimension as the older 5D Mark II with a button layout. It features a 100% viewfinder with 1x magnification, the 7D was the first Canon camera with a dedicated movie mode switch, instead of movie recording being done in live view as with the 5D Mark II and 500D. The 7D has dual DIGIC4 processors and can reach 8 frames per second continuous shooting, when the camera was first released, the buffer throughput allowed up to 94 frames in large fine JPEG mode, and up to 15 frames in RAW. Firmware upgrades, most recently in August 2012, have increased the maximum size to 130 large fine JPEGs and 25 RAW files. On 6 August 2012, new firmware v2.0.0, the Canon EOS 7D offers the ability to record audio from an external source. Both shutter and aperture are available for control, and the 7D provides multiple frame rate options. Like most DSLR modes, the Canon 7D neglects endless autofocus during video recording, larger memory cards make for longer video lengths and are available in multiple sizes for the camera.
The Canon 7D has acquired significance in the independent filmmaking world as an alternative to digital cinema cameras. The camera was used on the feature films Stanley Ka Dabba and Vazhakku Enn 18/9, product Page Firmware update cures residual image phenomenon