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Dictionary    photography
Whenever you need to check an art definition or find out about art techniques, our Londonart.co.uk Dictionary comes handy! If you are baffled by art terms and cannot differentiate between C-type photograph and giclee print browse our online, free dictionary. We provide definitions in four different categories: painting and drawing; art styles; photography; sculpture and craft. Just choose the area you are interested in and search for explanations.
ALBUMEN PRINT
Albumen paper is made by coating paper with albumen (egg white) mixed with ammonium or sodium chloride and allowing it to dry. The albumen coating enables more silver chloride to be present than in simple salted paper, so albumen prints are richer. All albumen prints slowly turn yellow as they get old.
ARCHIVAL
Archival processing requires materials to be processed to strict standards to keep residual amounts of processing chemicals to a low level so they can be stored for a long length of time. Even with good processing, most photographic prints have relatively short lifetimes. The most common film base material currently in use breaks down on long term storage, typically after 30-40 years.
BLACK AND WHITE
Black-and-white is a broad term used to describe a number of forms of visual technology. Most forms of visual technology start out in black and white and then slowly evolve into color as technology progresses.
BROMIDE PAPER
Bromide papers are coated with a light sensitive emulsion of silver bromide in gelatine. Usually there is a layer of baryta (barium sulphate) below the emulsion to increase the brightness, and a top layer of pure harder gelatin to act as a protection coat. Bromide papers are made for development and generally yield neutral to cool black prints.
CARBON PRINT
Carbon printing is a process which depends on the light sensitivity of dichromates. It starts with a 'carbon tissue' sheet of paper coated with gelatine containing a pigment, which is sensitised by a brief soak in a solution of potassium dichromate and then dried away from any sources of UV light. The images are reversed in the process.
CIBACHROME PRINT
Cibachrome prints are created from colour transparencies (slides) by a system that is completely different from regular colour prints. Cibachrome prints are made on a tri-acetate polyester base, meaning that your print will not fade, discolour or deteriorate for a very long time. They are also archival, and unlike regular colour prints, which fade over time, Cibachrome prints will last a lifetime.
COLLOTYPE
Collotype is a dichromate based process, developed for cheap large volume mechanical printing before the widespread use of still cheaper offset litho. It can produce results difficult to distinguish from actual photographs. Many old postcards are collotypes. It is used in fine art photography.
CONTRE-JOUR
Contre-jour means 'against the light' and refers to pictures taken when the camera is pointing towards (or roughly towards) the main light source. Portraits taken contre-jour will show a bright halo of light in the hair. Fill-in light will be needed to show detail in the face, or it can be kept dark to give a silhouette.
DAYLIGHT FILMS
Daylight films are color transparency films made for use in normal daylight conditions, designed for a color temperature of around 6000K in normal sunlight. Filtration is needed for lighting conditions other than normal daylight, unless deliberate color shifts are wanted. Filtration is not necessary for black and white film and with color negative a correction can be made in printing.
DIGITAL PHOTOGRAPHY
Digital photography uses an electronic sensor to record the image as binary data. This facilitates storage and editing of the images on personal computers. Digital cameras now outsell film cameras and include features not found in film cameras such as the ability to shoot video and record audio. Pixel count (typically listed in megapixels, millions of pixels) is only one of the major factors which show the quality of the camera, though it is the most heavily marketed.
DPI
DPI or dots per inch is used to describe the resolution of input and output devices such as scanners and printers. A resolution figure in dpi may also be embedded in a digital image file, but the image files themselves do not really have a resolution - it is an instruction about how they should be output. A 600 dpi scanner will take 600 readings per inch from points across the original it is scanning, then move to the next scan line and repeat the process.
EKTACHROME
Ektachrome is the name given to a range of transparency films produced by Kodak. They are available in most formats including 35mm and can be processed in just over an hour by small professional labs. Kodak now uses the Ektachrome brand for professional films only and amateur Kodak E-6 films are now branded Elite Chrome.
EMULSION
A photographic emulsion is the light sensitive layer of a film of paper. The emulsion is made of gelatin, and has small crystals of light sensitive silver halide (silver bromide, silver iodide or silver chloride) suspended in it. When placed in water, the gelatin absorbs large amounts of water, swelling up and allowing the photographic chemicals to reach the silver halide crystals.
FIBRE BASE PAPER
Fibre based paper is normal photographic paper coated on a paper base without a plastic coating. Fibre based papers can have bromide or chorobromide emulsions and be available as multigrade or single grade papers. Many photographers still use fibre based paper for high quality exhibition prints despite the greater convenience of RC papers.
GELATIN
Gelatin is a protein extracted from animal hides and used in a variety of foodstuffs to produce 'jellies'. In photography, gelatine is used to suspend the light sensitive silver halides and bind them to the film or paper base. The exact specification of the gelatin is important in making films, having an effect on the sensitivity, as does the 'ripening' process used to control the size and shape of the silver halide crystals in suspension in the gelatin.
GICLÉE PRINT
Giclée print is the 'gallery term' for inkjet prints, used to try and make them seem more valuable than prints you can make from your own computer. Inkjet printing covers a very wide range of printer types, ink compositions and papers, from cheap throwaway prints to works of art on fine paper printed on high quality printers. The first high quality inkjet prints available were from expensive 'Iris' printers, and these prints were called 'Iris Giclée'.
GUM BICHROMATE PRINT
Gum bichromate prints make use of the light sensitivity of dichromates. Light changes the dichromate into a material that hardens gum arabic (and other colloidal materials). Paper is coated with a mixture of gum arabic, a pigment (usually from a watercolor tube) and potassium or ammonium dichromate in dim light and allowed to dry.
HALFTONE
Halftones are the way that normal print processes for books and magazines create the impression of continuous tones and a full grayscale using only black ink and white paper. A mid gray will be given if the printer lays down black dots covering roughly half of the white paper, lighter grays if there is less coverage and darker grays with more. Colour halftones use cyan, yellow, magenta, and black (CMYK) dots in a similar way.
HAND-COLOURING
Hand-colouring refers to manually adding colour to a black-and-white photograph or other image to heighten its realism. Typically, watercolours, oils and other paints are applied to the image surface using brushes, fingers or airbrushes. Some photographic genres, particularly landscapes and portraits, have been more often hand-coloured than others.
ILFOCHROME
Ilfochrome (formerly Cibachrome) is a direct process for printing from transparencies, working by destroying dyes originally present in the material. It produces bright, punchy prints with generally good display properties, but tends to lack subtlety. It is probably most suited to low contrast transparencies.
INFRARED
Infrared radiation is electromagnetic radiation that has a wavelength just above what we see as red light. Infrared film is film that is sensitive to this radiation. All film is also sensitive to UV and infrared film will also be sensitive to visible light. To get the best infrared effects it is exposed using a deep red or opaque black (87C) filter.
INKJET PRINT
Inkjet prints are photographic prints that have been printed on a small inkjet printer. They have a reputation for being 'dotty' in areas of even tone and in particular in the highlights, and for rapid fading on display and in storage. Until recently, manufacturers of inkjet printers had paid little attention to print life, but this has begun to change with more recent models.
KODACHROME
Kodachrome is a brand of colour transparency (slide) film sold by Kodak and is widely regarded as one of the best films available for the consumer because of its fine grain and vivid color reproduction. The structure of the Kodachrome emulsion is fundamentally different from that of other slide films.
LAMBDA PRINT
In art and photography, a lambda-print is a positive image, usually a photograph, executed on photographic (light-sensitive) paper using a dedicated laser printer.
MONOCHROME
A monochromatic object has a single colour. For an image, the term monochrome means the same as black-and-white, but may also be used to refer to other combinations containing only two colors, such as green-and-white and green-and-black. It may also refer to sepia or cyanotype images.
OIL PRINT
Oil printing is based on the idea that water and oil repel each other. Gelatin coatings on paper can be hardened using dichromates and exposing to light under a negative. After washing out the dichromate the paper is then dried and resoaked in water. The hardened gelatine does not absorb water, while the soft unhardened material does.
PALLADIUM PRINT
Palladium prints are made using an iron based process are are virtually identical to platinum prints, except they are generally warmer in tone. Most platinum prints contain a mixture of platinum and palladium. Palladium is usually slightly cheaper than platinum and so is often used on its own by beginners at platinum printing.
PHOTOGENIC DRAWING
Photogenic drawing is the name given by W H F Talbot to his early experimental images made in the 1830s. These where generally made on writing paper that had been treated with salt and then with silver nitrate and were a crude form of the salted paper printing process he used later to print his calotype negatives.
PHOTOMONTAGE
Photomontage is the process (and result) of making a composite picture by cutting and joining a number of photographs. Other methods for combining pictures are also called photomontage, such as combination printing (the printing from more than one negative on a single piece of printing paper), front-projection and computer montage techniques.
PIGMENT PRINT
Pigment print is a general term for any kind of print which uses a pigment to produce the image, including gum, Fresson, carbon and carbro. Pigment prints are usually made using fairly stable pigments and thus should last well. Inkjet prints produced using pigment inks would not normally be included in this, although some also have long lifetimes.
PINHOLE CAMERA
A pinhole camera is a camera without a lens. The light producing the image passes through a small hole, and the shutter of a pinhole camera usually consists of a hand operated flap of some light-proof material to cover and uncover the pinhole. Pinhole cameras require much longer exposure times than conventional cameras because of the small aperture; typical exposure times can range from 5 seconds to more than an hour.
PIXEL
A pixel is short for a 'picture element', and is used to describe both a point on a display screen consisting of red, green and blue dots (with a strong magnifier you should be able to see these on your screen - though they may look more like lines as the dots tend to merge into each other) and also a point in an image file.
RESOLUTION
The resolution of lenses and films is determined by finding the smallest distance between lines that can clearly be distinguished when the image is examined using a microscope. Screen resolution is simply the number of dots per inch across the screen and is seldom the much quoted figure of 72dpi. Printer resolution is the number of possible dot positions per inch of output, although there are often complicating restrictions on which can actually be used
RETOUCHING
Retouching uses many of the same tools and techniques as hand-colouring, but with the intent of covering damage, hiding unwanted features, accentuating details, or adding missing elements in a photographic print. In a portrait, retouching could be used to improve a sitter's appearance, for instance, by removing facial blemishes, and in a landscape with an overexposed sky, clouds could be painted into the image.
SEPIA TONING
Sepia toning involves replacement of silver in the black and white photographic print by silver sulphide, which is brown. Silver sulphide is more stable than silver, so sulphide toning is a good archival technique that will increase expected print life.
SILVER GELATINE PRINT
Silver gelatine print is the gallery term for an ordinary black and white photograph. Whether bromide or chlorobromide, fibre base or resin coated, they all contain a silver image in a gelatine emulsion. Having special names like this perhaps makes it easier to charge higher prices than you would expect to pay if a lab was printing one of your own pictures.
SLR
A SLR is a single lens reflex camera. Light coming into the camera through the lens that takes pictures is reflected up by a mirror behind the lens onto a ground glass screen above. You look at this screen through the viewfinder and a 5 sided glass prism (a pentaprism) is used to turn the image the correct way round.
TINTED PHOTOGRAPHS
Tinted photographs are made with dyed printing papers produced by commercial manufacturers. A single overall colour underlies the image and is most apparent in the highlights and mid-tones. Over time colouration often becomes very faded.
TONING
Toning is altering the overall colour of the photographic image itself. Compounds of gold, platinum or other metals are used in combination with variations in development time, temperature and other factors to produce a range of tones, including warm browns, purples, sepias, blues, olives and blue-blacks. Besides adding colour to a monochromatic print, toning often improves image stability and increases contrast.