In digital photography and digital video, clipping is a result of capturing or processing an image where the intensity in a certain area falls outside the minimum and maximum intensity which can be represented. It is an instance of signal clipping in the image domain; the clipped area of the image will appear as a uniform area of the minimum or maximum brightness, losing any image detail. The amount by which values were clipped, the extent of the clipped area, affect the degree to which the clipping is visually noticeable or undesirable in the resulting image. In a color image, clipping may occur in any of the image's color channels separately. Clipping can occur at many different stages, it may occur in the image sensor when capturing the image using a digital camera or scanner. It may occur due to internal image color space conversion in the camera or scanner, it may result from image processing using image editing software. Clipping, due to internal image processing in a digital camera may be or recovered if the raw sensor data is available, such as when saving to a raw image format.
Clipping can occur in image highlights as a result of an incorrect exposure when photographing or scanning to a digital image. Increasing an exposure increases the amount of light collected or the sensitivity of the sensor, increasing it too far will cause the lightest areas, such as the sky, or light sources, to clip. Bright areas due to overexposure are sometimes called blown-out flared highlights. In extreme cases, the clipped area may appear to have a noticeable border between the clipped and non-clipped area; the clipped area will be white, though in the case that only one color channel has clipped, it may represent itself as an area of distorted color, such as an area of sky, greener or yellower than it should be. A similar effect of blown-out highlights exists in analog photography, though in that case it is not referred to as "clipping", the "blown-out" area curves off to its maximum brightness rather than being cut off abruptly as in clipping; this causes blown-out highlights to appear differently in analog and digital photography, with the smooth edges in analog photography regarded as more pleasant to some.
In some cases, a small amount of clipping may be tolerable when the clipped area is in the background of the image rather than part of the main subject, or is only a small area such as a specular highlight. Clipping in some color channels may occur when an image is rendered to a different color space, when the image contains colors that fall outside the target color space; such colors are referred to as out-of-gamut. This form of clipping may be avoided by performing the color space conversion using a different rendering intent. However, this can sometimes result in a lower overall color saturation; the desire for bright, saturated colors may, in some cases, be more important than avoiding clipping in single channels due to out-of-gamut colors. Clipping may occur in digital video, just as in digital still photography. Just as with digital still photography, an intensity value, outside the allowed range of values in any one channel causes clipping. High dynamic range Graduated neutral density filter What is white or black "clipping", how does one avoid it?
Understanding Digital Camera Histograms: Tones and Contrast
Black and white
Black-and-white images combine black and white in a continuous spectrum, producing a range of shades of gray. The history of various visual media has begun with black and white, as technology improved, altered to color. However, there are exceptions to this rule, including black-and-white fine art photography and in motion pictures, many art films. Most early forms of motion pictures or film were white; some color film processes, including hand coloring were experimented with, in limited use, from the earliest days of motion pictures. The switch from most films being in black-and-white to most being in color was gradual, taking place from the 1930s to the 1960s; when most film studios had the capability to make color films, the technology's popularity was limited, as using the Technicolor process was expensive and cumbersome. For many years, it was not possible for films in color to render realistic hues, thus its use was restricted to historical films and cartoons until the 1950s, while many directors preferred to use black-and-white stock.
For the years 1940–1966, a separate Academy Award for Best Art Direction was given for black-and-white movies along with one for color. The earliest television broadcasts were transmitted in black-and-white, received and displayed by black-and-white only television sets. Scottish inventor John Logie Baird demonstrated the world's first color television transmission on July 3, 1928 using a mechanical process; some color broadcasts in the U. S. began in the 1950s, with color becoming common in western industrialized nations during the late 1960s. In the United States, the Federal Communications Commission settled on a color NTSC standard in 1953, the NBC network began broadcasting a limited color television schedule in January 1954. Color television became more widespread in the U. S. between 1963 and 1967, when major networks like CBS and ABC joined NBC in broadcasting full color schedules. Some TV stations in the US were still broadcasting in B&W until the late 80s to early 90s, depending on network.
Canada began airing color television in 1966 while the United Kingdom began to use an different color system from July 1967 known as PAL. The Republic of Ireland followed in 1970. Australia experimented with color television in 1967 but continued to broadcast in black-and-white until 1975, New Zealand experimented with color broadcasting in 1973 but didn't convert until 1975. In China, black-and-white television sets were the norm until as late as the 1990s, color TVs not outselling them until about 1989. In 1969, Japanese electronics manufacturers standardized the first format for industrial/non-broadcast videotape recorders called EIAJ-1, which offered only black-and-white video recording and playback. While used professionally now, many consumer camcorders have the ability to record in black-and-white. Throughout the 19th century, most photography was monochrome photography: images were either black-and-white or shades of sepia. Personal and commercial photographs might be hand tinted. Colour photography was rare and expensive and again containing inaccurate hues.
Color photography became more common from the mid-20th century. However, black-and-white photography has continued to be a popular medium for art photography, as shown in the picture by the well-known photographer Ansel Adams; this can take the form of black-and-white film or digital conversion to grayscale, with optional digital image editing manipulation to enhance the results. For amateur use certain companies such as Kodak manufactured black-and-white disposable cameras until 2009. Certain films are produced today which give black-and-white images using the ubiquitous C41 color process. Printing is an ancient art, color printing has been possible in some ways from the time colored inks were produced. In the modern era, for financial and other practical reasons, black-and-white printing has been common through the 20th century. However, with the technology of the 21st century, home color printers, which can produce color photographs, are common and inexpensive, a technology unimaginable in the mid-20th century.
Most American newspapers were black-and-white until the early 1980s. Some claim. In the UK, color was only introduced from the mid-1980s. Today, many newspapers restrict color photographs to the front and other prominent pages since mass-producing photographs in black-and-white is less expensive than color. Daily comic strips in newspapers were traditionally black-and-white with color reserved for Sunday strips.:Color printing is more expensive. Sometimes color is reserved for the cover. Magazines such as Jet magazine were either all or black-and-white until the end of the 2000s when it became all-color. Manga are published in black-and-white although now it is part of its image. Many school yearbooks are still or in black-and-white; the Wizard of Oz is in color when Dorothy is in Oz, but in black-and-white when she is in Kansas, although the latter scenes were in sepia when the film was released. The British film A Matter of Life and Death depicts the other world in black-and-white, earthly events in color.
Wim Wenders's film Wings of Desire uses sepia-tone black-and-white f
In photography, exposure value is a number that represents a combination of a camera's shutter speed and f-number, such that all combinations that yield the same exposure have the same EV. Exposure value is used to indicate an interval on the photographic exposure scale, with a difference of 1 EV corresponding to a standard power-of-2 exposure step referred to as a stop; the EV concept was developed by the German shutter manufacturer Friedrich Deckel in the 1950s. Its intent was to simplify choosing among equivalent camera exposure settings by replacing combinations of shutter speed and f-number with a single number. On some lenses with leaf shutters, the process was further simplified by allowing the shutter and aperture controls to be linked such that, when one was changed, the other was automatically adjusted to maintain the same exposure; this was helpful to beginners with limited understanding of the effects of shutter speed and aperture and the relationship between them. But it was useful for experienced photographers who might choose a shutter speed to stop motion or an f-number for depth of field, because it allowed for faster adjustment—without the need for mental calculations—and reduced the chance of error when making the adjustment.
The concept became known as the Light Value System in Europe. Because of mechanical considerations, the coupling of shutter and aperture was limited to lenses with leaf shutters; the proper EV was determined by the scene film speed. With all of these elements included, the camera would be set by transferring the single number thus determined. Exposure value has been indicated in various ways; the ASA and ANSI standards used the quantity symbol Ev, with the subscript v indicating the logarithmic value. The Exif standard uses Ev. Although all camera settings with the same EV nominally give the same exposure, they do not give the same picture; the f-number determines the depth of field, the shutter speed determines the amount of motion blur, as illustrated by the two images at the right. Exposure value is a base-2 logarithmic scale defined by: E V = log 2 N 2 t, where N is the relative aperture t is the exposure time in secondsEV 0 corresponds to an exposure time of 1 s and a relative aperture of f/1.0.
If the EV is known, it can be used to select combinations of exposure time and f-number, as shown in Table 1. Each increment of 1 in exposure value corresponds to a change of one "step" in exposure, i.e. half as much exposure, either by halving the exposure time or halving the aperture area, or a combination of such changes. Greater exposure values are appropriate for photography in more brightly lit situations, or for higher ISO speeds. "Exposure value" indicates combinations of camera settings rather than the luminous exposure, given by H = E t, where H is the luminous/photometric exposure E is the image-plane illuminance t is the exposure time The illuminance E is controlled by the f-number but depends on the scene luminance. To avoid confusion, some authors have used camera exposure to refer to combinations of camera settings; the 1964 ASA standard for automatic exposure controls for cameras, ASA PH2.15-1964, took the same approach, used the more descriptive term camera exposure settings.
Common practice among photographers is nonetheless to use "exposure" to refer to camera settings as well as to photometric exposure. The image-plane illuminance is directly proportional to the area of the aperture, hence inversely proportional to the square of the lens f-number. If, for example, the f-number is changed, an equivalent exposure time can be determined from t 2 t 1 = N 2 2 N 1 2. Performing this calculation mentally is tedious for most photographers, but the equation is solved with a calculator dial on an exposure meter or a similar dial on a standalone calculator. If the camera controls have detents, constant exposure can be maintained by counting the steps as one control is adjusted and counting an equivalent number of steps when adjusting the other control; the ratio t/N2 could be used to represent equivalent combinations of exposure time and f-number in a single value. B
Royal Photographic Society
The Royal Photographic Society of Great Britain known as the Royal Photographic Society, is one of the world's oldest photographic societies. It was founded in London, England, in 1853 as The Photographic Society of London with the objective of promoting the art and science of photography, in 1854 received Royal patronage from Queen Victoria and Prince Albert. A change to the society's name to reflect the Royal patronage was, not considered expedient at the time. In 1874 it was renamed the Photographic Society of Great Britain, from 1894 it became known as The Royal Photographic Society of Great Britain. A registered charity since 1962, in July 2004, The Royal Photographic Society of Great Britain was granted a Royal charter recognising its eminence in the field of photography as a learned society. For most of its history the Society was based at various premises in London, it moved to Bath in 1979, since 2004 its headquarters has been at Fenton House in Bath, England. Membership is open to anyone with an interest in photography.
In addition to standard membership, the Society offers three levels of distinctions which set recognised standards of achievement throughout the world, can be applied for by both members and non-members: Licentiate and Fellow, in all aspects of photography and vocational qualifications in the areas of Creative Industries and Imaging Science. It runs an extensive programme of more than 300 events throughout the United Kingdom and abroad, through local groups and special interest groups; the Society acts as a national voice for photographers and for photography more and it represents these interests on a range of governmental and national bodies dealing with areas as diverse as copyright and photographers' rights. The Society's collection of historic photographs, photographic equipment and books was deposited for the nation at the National Science and Media Museum in Bradford in 2003, but most of the collection is moving to the Victoria and Albert Museum in London. Photographers were slow in forming clubs and societies.
The first was an informal grouping the Edinburgh Calotype Club around 1843 and the first photographic society, the Leeds Photographic Society in 1852 and claims to be the oldest photographic society in the world, although it had a break between 1878 and 1881 when it ceased to exist independently. In other countries the Société française de photographie was founded in Paris in 1854; the catalyst behind the formation of The Photographic Society was Roger Fenton. The Great Exhibition of 1851 had raised public awareness of photography and in December 1852 an exhibition of nearly 800 photographs at The Society of Arts had brought together amateur and professional photographers; the inaugural meeting of The Photographic Society was held on 20 January 1853. Fenton became a position he held for three years; as Jane Fletcher has argued the changing nature of photography and photographic education in the early 1970s forced The Society to modernise and to become more relevant to British photography. An internal review led to constitutional changes, the introduction of a new distinction called the Licentiate in 1972 and six new specialist groups were established.
The rising cost of maintaining The Society's premises in South Audley Street, London led the Society's Executive Committee to look for alternative premises. The Council approved at a meeting on 1 April 1977 a move to Bath and the establishment of a National Centre of Photography to house the Society's headquarters and collection. An appeal for £300,000 was launched in the summer of 1978 for the funds needed to convert The Octagon and adjacent buildings in Milsom Street, Bath; the inaugural exhibition opened in May 1980 with the building opened by Princess Margaret in April 1981. Although the Society's inaugural meeting took places at the Society of Arts in London, it was some time before the Society had its own permanent home, it held functions as a number of some concurrently for different types of meetings. Premises used were: Royal Society of John Adam Street; the Society's premises were: 1899 -- 1909 -- London. 1909–1940 – 35 Russell Square, London. 1940–1968 – Princes Gate, South Kensington, London.
1968–1970 – 1 Maddox Street, London. 1970–1979 – 14 South Audley Street, London 1980–2003 – The Octagon, Milsom Street, Bath. 2004–January 2019 – Fenton House, 122 Wells Road, Bath. 7 February 2019 – Paintworks, Bath Road, Bristol. The Society had collected photographs and items of historical importance on an ad hoc basis but there was no formal collecting policy until John Dudley Johnston was appointed Honorary Curator a post he held between 1924 and 1955. Up to Johnston's appointment the collection has concentrated on technical advances of photography and Johnston began to concentrate on adding pictorial photography to the collection. On Johnston's death in 1955 his role of Honorary Curator was taken over by his wife Florence and a succession of paid and unpaid staff including Gail Buckland, Carolyn Bloore, Arthur Gill, Valerie Lloyd, Brian Coe, with Professor Margaret Harker as Honorary Curator over a long period. Pam Roberts was appointed curator, a position she held until the collection was closed in 2001 pending its transfer to the National Museum of Photography and Television in 2002.
The move was supported by the Head of the museum
An optical filter is a device that selectively transmits light of different wavelengths implemented as a glass plane or plastic device in the optical path, which are either dyed in the bulk or have interference coatings. The optical properties of filters are described by their frequency response, which specifies how the magnitude and phase of each frequency component of an incoming signal is modified by the filter. Filters belong to one of two categories; the simplest, physically, is the absorptive filter. Optical filters selectively transmit light in a particular range of wavelengths, that is, while absorbing the remainder, they can pass long wavelengths only, short wavelengths only, or a band of wavelengths, blocking both longer and shorter wavelengths. The passband may be wider. There are filters with more complex transmission characteristic, for example with two peaks rather than a single band. Optical filters are used in photography, in many optical instruments, to colour stage lighting. In astronomy optical filters are used to restrict light passed to the spectral band of interest, e.g. to study infrared radiation without visible light which would affect film or sensors and overwhelm the desired infrared.
Optical filters are essential in fluorescence applications such as fluorescence microscopy and fluorescence spectroscopy. Photographic filters are a particular case of optical filters, much of the material here applies. Photographic filters do not need the controlled optical properties and defined transmission curves of filters designed for scientific work, sell in larger quantities at correspondingly lower prices than many laboratory filters; some photographic effect filters, such as star effect filters, are not relevant to scientific work. Absorptive filters are made from glass to which various inorganic or organic compounds have been added; these compounds absorb some wavelengths of light while transmitting others. The compounds can be added to plastic to produce gel filters, which are lighter and cheaper than glass-based filters. Alternately, dichroic filters can be made by coating a glass substrate with a series of optical coatings. Dichroic filters reflect the unwanted portion of the light and transmit the remainder.
Dichroic filters use the principle of interference. Their layers form a sequential series of reflective cavities that resonate with the desired wavelengths. Other wavelengths destructively reflect as the peaks and troughs of the waves overlap. Dichroic filters are suited for precise scientific work, since their exact colour range can be controlled by the thickness and sequence of the coatings, they are much more expensive and delicate than absorption filters. They can be used in devices such as the dichroic prism of a camera to separate a beam of light into different coloured components; the basic scientific instrument of this type is a Fabry–Pérot interferometer. It uses two mirrors to establish a resonating cavity, it passes wavelengths. Etalons are another variation: transparent cubes or fibers whose polished ends form mirrors tuned to resonate with specific wavelengths; these are used to separate channels in telecommunications networks that use wavelength division multiplexing on long-haul optic fibers.
Monochromatic filters only allow a narrow range of wavelengths to pass. The term "infrared filter" can be ambiguous, as it may be applied to filters to pass infrared or to block infrared. Infrared-passing filters pass infrared. Infrared cut-off filters are designed to block or reflect infrared wavelengths but pass visible light. Mid-infrared filters are used as heat-absorbing filters in devices with bright incandescent light bulbs to prevent unwanted heating due to infrared radiation. There are filters which are used in solid state video cameras to block IR due to the high sensitivity of many camera sensors to unwanted near-infrared light. Ultraviolet filters let visible light through; because photographic film and digital sensors are sensitive to ultraviolet but the human eye is not, such light would, if not filtered out, make photographs look different from the scene visible to people, for example making images of distant mountains appear unnaturally hazy. An ultraviolet-blocking filter renders images closer to the visual appearance of the scene.
As with infrared filters there is a potential ambiguity between UV-passing filters. Neutral density filters have a constant attenuation across the range of visible wavelengths, are used to reduce the intensity of light by reflecting or absorbing a portion of it, they are specified by the optical density of the filter, the negative of the common logarithm of the transmission coefficient. They are useful for making photographic exposures longer. A practical example is making
High-dynamic-range imaging is a high dynamic range technique used in imaging and photography to reproduce a greater dynamic range of luminosity than is possible with standard digital imaging or photographic techniques. The aim is to present a similar range of luminance to that experienced through the human visual system; the human eye, through adaptation of the iris and other methods, adjusts to adapt to a broad range of luminance present in the environment. The brain continuously interprets this information so that a viewer can see in a wide range of light conditions. HDR images can represent a greater range of luminance levels than can be achieved using more traditional methods, such as many real-world scenes containing bright, direct sunlight to extreme shade, or faint nebulae; this is achieved by capturing and combining several different, narrower range, exposures of the same subject matter. Non-HDR cameras take photographs with a limited exposure range, referred to as LDR, resulting in the loss of detail in highlights or shadows.
The two primary types of HDR images are computer renderings and images resulting from merging multiple low-dynamic-range or standard-dynamic-range photographs. HDR images can be acquired using special image sensors, such as an oversampled binary image sensor. Due to the limitations of printing and display contrast, the extended luminosity range of an HDR image has to be compressed to be made visible; the method of rendering an HDR image to a standard monitor or printing device is called tone mapping. This method reduces the overall contrast of an HDR image to facilitate display on devices or printouts with lower dynamic range, can be applied to produce images with preserved local contrast. In photography, dynamic range is measured in exposure value differences. An increase of one EV, or'one stop', represents a doubling of the amount of light. Conversely, a decrease of one EV represents a halving of the amount of light. Therefore, revealing detail in the darkest of shadows requires high exposures, while preserving detail in bright situations requires low exposures.
Most cameras cannot provide this range of exposure values within a single exposure, due to their low dynamic range. High-dynamic-range photographs are achieved by capturing multiple standard-exposure images using exposure bracketing, later merging them into a single HDR image within a photo manipulation program). Digital images are encoded in a camera's raw image format, because 8-bit JPEG encoding does not offer a wide enough range of values to allow fine transitions. Any camera that allows manual exposure control can make images for HDR work, although one equipped with auto exposure bracketing is far better suited. Images from film cameras are less suitable as they must first be digitized, so that they can be processed using software HDR methods. In most imaging devices, the degree of exposure to light applied to the active element can be altered in one of two ways: by either increasing/decreasing the size of the aperture or by increasing/decreasing the time of each exposure. Exposure variation in an HDR set is only done by altering the exposure time and not the aperture size.
An important limitation for HDR photography is that any movement between successive images will impede or prevent success in combining them afterward. As one must create several images to obtain the desired luminance range, such a full'set' of images takes extra time. HDR photographers have developed calculation methods and techniques to overcome these problems, but the use of a sturdy tripod is, at least, advised; some cameras have an auto exposure bracketing feature with a far greater dynamic range than others, from the 3 EV of the Canon EOS 40D, to the 18 EV of the Canon EOS-1D Mark II. As the popularity of this imaging method grows, several camera manufacturers are now offering built-in HDR features. For example, the Pentax K-7 DSLR has an HDR mode that captures an HDR image and outputs a tone mapped JPEG file; the Canon PowerShot G12, Canon PowerShot S95 and Canon PowerShot S100 offer similar features in a smaller format. Nikon's approach is called'Active D-Lighting' which applies exposure compensation and tone mapping to the image as it comes from the sensor, with the emphasis being on creating a realistic effect.
Some smartphones provide HDR modes, most mobile platforms have apps that provide HDR picture taking. Camera characteristics such as gamma curves, sensor resolution, photometric calibration and color calibration affect resulting high-dynamic-range images. Color film negatives and slides consist of multiple film layers; as a consequence, transparent originals feature a high dynamic range. Tone mapping reduces the dynamic range, or contrast ratio, of an entire image while retaining localized contrast. Although it is a distinct operation, tone mapping is applied to HDRI files by the same software package. Several software applications are available on the PC, Mac and Linux platforms for producing HDR files and tone mapped images. Notable titles include Information stored in high-dynamic-range images corresponds to the physical values of luminance or radiance that can be observed in the real world; this is different from traditional digital images, which represent
Cokin is a French manufacturer of optical filters for photography. The system allows filters such as rectangular graduated neutral density filters which are versatile in use. Cokin are noted for their "Creative Filter System", it was invented by photographer Jean Coquin and introduced in 1978. Based around square filters, these require a holder, attached to the lens via a simple adapter ring of the appropriate size. Unlike screw-thread circular filters, which are each tied to lenses of a specific diameter, those in the system can be used with any lens, provided they are large enough to cover it sufficiently.. The system includes a wide range of filters including color correction and coloured graduated filters, diffraction and polarizers; the material is a polymer, CR-39 sometimes advertised as "organic glass". Cokin produce various differently-sized versions of the Creative Filter System; the smallest is "A". The larger "P" system covers cases where "A" filters are too small to cover the lens; the still-larger "X-Pro" filters are 130mm wide.
The "A" and "P" sizes in particular are de facto standards, with many other manufacturers producing compatible filters and holders. Cokin produce a system for 100mm-wide filters which they refer to as "Z-Pro". "X-Pro" and "Z-Pro" are designed for larger cameras. Cokin UK website