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c

C-41

Processing system for colour negative film.

C-mount

A threaded means of mounting a lens to a camera.

Cable release

Its a flexible cable used for firing a camera shutter. Particularly useful for slow shutter speed and time exposures, when touching the camera may cause camera vibration and blurring of the image.

Cache

A temporary storage area for information which locates itself between the hard disk and the RAM by employing intuitive logic. It also speeds up access time of the data.

Calibration

The act of adjusting the colour of one device relative to another, such as a monitor to a printer, or a scanner to a film recorder. Or, it may be the process of adjusting the colour of one device to some established standard.

Calibration bars

An 11-step grayscale in 10% increments from 0% to 100% that prints along the edge of a page. When outputting colour separations a progressive colour bar is also printed. Calibration bars can be read with a densitometer to insure accurate output and printing.

Camera angles

Various positions of the camera with respect to the subject being photographed, each giving a different viewpoint and perspective.

Camera movements

Are mechanical system most common on large format camera which provide the facility for lens and film plane movement from a normal standard position.

Camera shake

Movement of camera caused by unsteady hold or support, vibration, etc., leading, particularly at slower shutter speeds, to a blurred image on the film. It is a major cause of un-sharp pictures, especially with long focus lenses.

Candle meter

Also known as a lux and defined as the illumination measured on a surface at a distance of one meter from a light source of one international candle power.

Capacity

The amount of information, measured in bytes, that can be stored on a hard drive. Also known as storage capacity.

Caption

Text that provided detailed information about the image such as, who, what, where, why, when and where. Photo credit, source, date, caption editor and other IPTC information

Capture

Acquiring an image by a scanner or digital camera.

Card reader

An Electronic device, which is connected to your computer to transfer pictures from memory cards from digital cameras to your computer.

Carriage

Part of a flatbed scanner that travels the length of the scanner bed. The illuminating lamp is mounted on the carriage to provide light for the image. In a CCD scanner, the carriage has mirrors mounted on it which reflect the image back to the CCD. In a CIS scanner, the carriage contains the CIS elements. Also Known as a scanhead.

Cast

An image's overall shift in colour at any point in the process, from photography to scanning and image processing. The almost white and almost black areas of an image tend to take on a colour -- often red, blue, or yellow -- and display an unnatural appearance.

Catchlight

The reflection of a light in the subject's eyes in a portrait.

Cathode ray tube ( CRT )

Standard monitors for computers are CRTs. CRTs use the colours of red, green, and blue for display.

CC filters

Yellow, Magenta, Cyan, Red, Green and blue filters that can change the colour balance of the resulting pictures. These filters are most useful for duplicating slides. They come in a range of densities from 0.025 to 0.50 . They are designated by the letters CC the density (without the decimal), and a letter indicating the hue, for example CC10M.

CCD

Charged Coupled Device, a light sensitive chip used for image gathering. In their normal condition these are grayscale devices. To create a colour pattern is laid down on the sensor pixels, using RGBG colour mask. (Red, Green, Blue, and Green) The extra Green is used to create contrast in the image. The CCD Pixels gather the colour from the light and pass it to the shift register for storage. * CCD are analog sensors, the digitizing happens when the electrons are passed through the A to D converter. The A to D converter converts the analog signal to a digital file or signal. Types of CCD's: Area CCD; A square or rectangular CCD that can capture an entire image at once, which is essential for dynamic subjects and flash photography; Linear CCD: Scanner-type CCD, these sensors are long and thin, and capture an image by recording a vast number of individual "exposures" while scanning across the picture frame. These are best suited for still subjects and continuous illumination.

CD

Compact Disc- A read only storage media typically capable of holding up to 650 MB of data.

CD burning

Saving your digital file to a CD. Usually, after we scan an image, we burn it to CD and send it to you.

CD-R

Compact Disc Recordable writes data to discs, which can then be read by standard CD-ROM drives.

CD-ROM

Compact Disc-read Only Memory. A CD-ROM drives uses the CD (compact disc) format as a computer storage medium. One CD can store 640 megabytes of data and other mixed media on a disc about the size of a traditional 5-1/4 in. floppy disk.

Center weighted

Refers to the area of the picture that the camera will meter for exposure. When making an auto exposure the camera is programmed to look at a number of spots in the scene, and if the camera was designed to use center weighted metering, most of those spots will be in the center area of the picture. (See Bottom weighted and exposure.)

Centering

Positioning a image properly within the digital field of vision so that it is framed appropriately.

Changing Bag

A light proof black fabric bag that permits film and other light-sensitive materials to be handled in normal room light. Has a double zipper on one end and two armholes with elastic sleeves on the other.

Channel

Photoshop uses the term Channels to describes black and white and colour image data. In Photoshop, one channel id typically defined as having up to eight bits of grayscale image information. Continuous tone images created with a scanner use channels as a way to describe the black and white and colour image data. A black and white grayscale image has one channel. An RGB colour image has three channels. A CMYK colour image has four channels. It is possible to have up to 24 channels in photoshop.

Characteristic curve

A graphic representation of the relationship of the film's exposure to light and the density of the resulting image. Also called the D log E curve, since density is plotted against the logarithm of the exposure.

Characterization

The process of creating an ICC profile that describes the unique colour characteristics of a particular device such as a monitor, scanner, colour printer, and printing press. Press profiles may be based on standards such as SWOP. Resultant ICC profiles define the gamut of a device in the context of a device-independent colour space so that colours may be mapped to or from the device gamut.

Chroma

The quality of a colour that is the combination of hue and brightness. In the Munsell system of colour notation, chroma indicates the purity of a colour as measured along an axis; the farther from the axis, the purer the colour.

Chromatic aberration

An optical defect of a lens which causes different colours or wave lengths of light to be focused at different distances from the lens. It is seen as colour fringes or halos along edges and around every point in the image.

Chromaticity

The colour quality of light which is defined by the wavelength ( hue ) and saturation. Chromaticity defines all the qualities of colour except its brightness.

Chrominance

A colour term defining the hue and saturation of a colour. Does not refer to brightness.

Cibachrome

a photographic process by which a print is made directly from a colour transparency. It is noted for rich colour, brilliant clarity, and outstanding archival-quality for colour prints. Also called Ilfochrome.

CIE

Commission Internationale de L'Éclairage. An international group that developed a universal set of colour definition standards in 1932.

CIE LAB ( L*a*b* )

A colour model to approximate human vision. The model consists of three variables: L* for luminosity, a* for one colour axis, and b* for the other colour axis.

Circle of confusion

Any sufficiently small circle is indistinguishable to the human eye from a point. As long as a lens resolves a point as a circle that is small enough, its resolution is adequate: though a lot depends on how much the image is to be enlarged, and the lighting conditions under which it is to be displayed, to say nothing of variations in individual eyesight. The size of the circle of confusion is a matter of dispute, especially with classic large format lenses.

Clearing Agent

A chemical that neutralizes hypo in film or paper, reducing wash time and helping to provide a more stable image.

Clearing time

Is the length of time needed for a negative to clear in a fixing solution.

Clip art

Graphic files that are usually distributed on CD-ROMS and can be inserted into documents, presentations, and projects.

Clipping

The removal of some portion of an input signal or quantity from the resulting output, generally by setting certain low and high thresholds and discarding the data that falls below the low threshold or above the high.

Clock Speed

The speed of the computer is measured by electronic circuits in an internal timing device.

Cloning

To make an exact duplicate of digital image data. In digital systems it is possible to copy part of an image onto another.

Close-up

A general term for an image of a close subject, i.e. filling the frame.

Close-up lens

A lens attachment placed in front of a camera lens to permit taking pictures at a closer distance than the camera lens alone will allow.

Clut ( Colour Look-Up Table )

A colour indexing system used by some computers to reference colour if their systems do not support a high bit depth to represent all colours.

CMOS

(Complementary Metal Oxide Semiconductor) A sensor similar to CCD. CMOS semiconductors use two circuits, negative and positive polarity circuits. Because only one of the circuits can be on at once, CMOS chips are less energy consuming than other chips that utilize simply one type of transistor. This is a clear advantage of the CMOS sensor over the standard CCDs in use today.

CMS

"Colour management system" This ensures colour uniformity across input and output devices so that final printed results match the original.

CMY

Cyan, Magenta, Yellow. The three subtractive colour primaries.

CMYK

Cyan, Magenta, Yellow, Black; These are the printer colours used to create colour prints. Most Colour Printers, Ink-Jet, Laser, Dye-Sublimation, Thermal, and Crayon printers use these as their printer colours. (This is one of the colour management problems for computers. Converting RGB files to CMYK files causes colour shifts.) When used by a printer the CMYK is also known as a reflective colour since it is printed on paper, or reflective films

Coated lens

A lens with air-glass surfaces which have been coated with magnesium fluoride to reduce lens flare. A coated lens is faster ( transmits more light ) than an uncoated lens.

Code notch

Individually distinctive notches located near one corner on photographic sheet of film for product identification purposes. When viewed correctly, these code notches will appear at top-left corner or bottom-right corner of the sheet. In this position the emulsion layer is always facing away from the observer.

Cold colours

Are colours at the blue end of the spectrum that suggest a cool atmosphere.

Color Densitometer

A piece of equipment used by press personnel to determine the density of the ink color being laid down on the printed sheet. It has a numerical digital read out and the higher the readout on the densitometer, the greater the amount of ink that is being laid down on the sheet.

Colorant

A dye, ink, pigment, wax, or other material used to impart colour.

Colorimeter

A precision instrument used to accurately measure tristimulus value of a colour in the way the human response system sees colours. Typically colorimeters are used to measure the Red, Green and Blue components of a light source, such as a colour monitor.

Colour balance

The overall hue of the colour in a colour reproduction. Correct colour balance implies that the colours in the scene are reproduced satisfactorily for the desired effect or realistic duplication. Referring to colour films, they are balanced in manufacture for exposure to light of a certain colour quality ; i.e., daylight, tungsten, ect.

Colour banding

The appearance of visible bands of colours that replace subtle gradations in order to accommodate a reduced palette.

Colour calibration

The process of ensuring accurate reproduction of colour for images. Full colour calibration is usually a two-step process: calibrating your input device, such as a scanner; and calibrating your output device, such as a printer or monitor. By calibrating input and output devices correctly, colour is accurately captured by your scanner and is reproduced faithfully on your monitor or printer as well.

Colour cast

The effect of one colour dominating the overall look of an image. Often caused by improper exposure, wrong film type, or unusual lighting conditions when shooting the original image. Also caused, when scanning, by the sometimes unpredictable interaction between an image and a scanner.

Colour channel

Refers to the Red, Green and Blue components from which colours are created.

Colour compensating filters

Gelatin filters that can be used to adjust the colour balance during picture taking or in colour printing. Abbreviated CC filters.

Colour conversion filters

Deeply coloured filters that enables colour film to be used with light of a different colour temperature than it was intended. The 80-series filters are blue enabling you to use daylight-balance film with tungsten light; the 85-series are amber and let you see tungsten film with daylight or electronic flash.

Colour correction

The process of adjusting an image to compensate for scanner deficiencies or for the characteristics of the output device.

Colour coupler

A colorless substance contained in colour film emulsions that, when exposed to chemical developing baths forms the colour dyes that make up part of the layers of processed colour films.

Colour curves

A mechanism for controlling colour changes, and matching colours. Colour curves are set by user-adjustable lookup tables that define a colour transform, which may be applied to each primary additive colour in the image.

Colour depth

The amount of colour information recorded by each CCD pixels. The greater the depth, expressed in bits, the truer and richer the colour is recorded.

Colour engine

The colour matching method used in a colour management system to convert the image data from the colour space of the source profile to the colour space of the destination profile.

Colour gamut

The range of colours that can be formed by all possible combination of colorants in any colour input system.

Colour head

A device on a enlarger that contains adjustable built-in filters (yellow, cyan and magenta) for colour printing.

Colour intensity

A feature found on most inkjet printers that controls the brightness of an image by varying the amount of ink applied to the page; lighter images use less ink and darker images use more.

Colour management

System that attempt to produce consistency in the representation of colour in image files, across image capture, display, and output devices.

Colour match RGB

The RGB working space that is the native colour space of Radius Press view monitors. This space provides a smaller gamut alternative to Adobe RGB (1998) for print production work.

Colour model

A colour measurement scale or system that numerically specifies the perceived attributes of colour. Used in computer graphics applications and by colour measurement instruments.

Colour negative

Film processed as a negative image from which positive prints can be made.

Colour Palette

Things are displayed on your monitor according to a specified number of colours in a color palette, e.g.: 256 colours. The theory is that more colours = more vivid picture quality. The number of colours a display is set to effects the entire look of the desktop, and correspondingly, the way applications look.

Colour passes

The number of times the carriage assembly of a scanner must pass over an object in order to achieve it's full potential colour depth.

Colour picker

The colour picker allows you to choose or define colours for the background or foreground colours using a colour spectrum or numerical values.

Colour printing filters

Yellow, Magenta and Cyan filters used when making colour prints, in order render the colours correctly or as desired. They come in a range of density from 0.025 to 0.50.

Colour profile

A representation of the colour properties of a device; colour space. Today, virtually all profiles conform to the ICC specification.

Colour quantization

The process of finding the best set of colours (palette) for representing an image. Two common methods are "median cut," which works best for real-world (scanned or photographed) images, and "popularity," which does well for drawn images. The popularity method simply picks the n colours used the most in the image. This tends to omit colours for highlights in photographs, which are important, although not the most popular. The median cut method assigns all available colours to groupings, then splits the groupings to determine a representative set of colours. The more bits available for each colour component, the more memory and time required to quantize, and the better colour matches that are obtained.

Colour reversal

Film designed to produce a normal colour positive on the film exposed in the camera for subsequent viewing by transmitted light.

Colour saturation

The purity of a colour resulting from the absence of black and white.

Colour sensitivity

Response of a sensitive material to colours of different wavelengths.

Colour separation

Conversion of RGB colour information into its cyan, magenta, yellow and black constituents.

Colour space

Colour spaces describe how the red, green and blue primaries are mixed to form a given hue in the colour spectrum. Since it is not possible to represent every colour in the visible spectrum *exactly* by mixing amounts of red, green and blue, colour spaces allow us to change how we define red, green and blue (and white) to get better colour reproduction. By "tweaking" primaries in this way, we can maximize how many colours *can* be accurately represented on monitors, printers, etc. by matching the colour space closely to what the device is capable of reproducing. There are also colour spaces designed for photo editing that don't match *any* particular device, but are instead designed to give more "coverage" of the overall colour gamut (spectrum of visible light) for the purpose of photo editing.

Colour temperature

The temperature (measured in degrees Kelvin) to which an object would have to be heated before it would radiate a given colour. Each type of light can also be represented by a numerical colour temperature, here are the (rough) colour temperatures of typical lighting conditions: Incandescent 2500K - 3500K; Twilight 4000K; Fluorescent 4000K - 4800K; Sunlight 4800K - 5400K; Cloudy daylight 5400K - 6200K; Shade 6200K - 7800K;

Colour temperature meter

A device for estimating the colour temperature of a light source. Usually used to determine the filtration needed to match the colour balance of the light source with that of standard types of colour film.

Colour value

A mathematically calculated value of a pixel's colour based on its colour components.

Colour value

A mathematically calculated value of a pixel's colour based on its colour components.

Colour wheel

The visible spectrum's continuum of colours arranged into a circle, where complementary colours such as red and green are located directly across from each other.

Colour-correction filter

Filters used with Black-and-white film to correct for the difference in films sensitivity to colour as compared with that of the human eye. Without a filter, for example clouds would be all but invisible against a light blue sky; a yellow filter would darken the sky, thus creating contrast between the sky and the clouds.

Coma

A lens aberration or defect that causes rays that passes obliquely through the lens to be focused at different points on the film plane.

CompactFlash

Flash memory card measuring 1.5 inches square, developed by Scandisk; used in small portable devices such as digital cameras, MP3 players and PDA's and available in a variety of multi-megabyte capacities. The controller is built onto these cards, so as new and faster controllers are designed you can purchase the newer card and take advantage of faster write time. These tend to be a bit more expensive than Smartmedia ( SSFDC ) cards. Any device that is designed to use a CF card can use any brand of CF cards so long as it meets the CFA ( Compact Flash Association ) standards ( virtually all of them do ). These are palmtop computers, voice recorders, and other devices that can use the same cards as your CF compatible camera.

Compatibility

The ability for data, programs (software) and equipment (hardware) to run and/or work together. This allows for the individual components to be put together to form a system.

Compensating developer

A developer designed to compress the general contrast range in a negative without influencing gradation in the shadow and highlight areas.

Complementary colours

1. Any two colours of light that when combined include all the wavelengths of light and thus produce white light. 2. Any two dye colours that when combined absorbs all wavelengths of light and thus produce black. A colour filter absorbs light of its complementary colour and passes light of its own colour.

Composition

The arrangement of the elements within a photograph--the main subject, the foreground and background, and supporting objects.

Compound shutter

Is a shutter consisting of a number of metal leaves arranged symmetrically around the edge of the lens barrel

Compressed A compressed image is one whose file size has been reduced. Some compression schemes maintain the quality of the image (lossless) and some do not (lossy or destructive). See also Compression

Compression

The process of reducing the size of a digital file, usually through software. This speeds processing, transmission time and reduces storage requirements.

Compur shutter

A well known German brand of compound shutter.

Condenser

An optical system which concentrates light rays from a wide source into a narrow beam. Condensers are used in spotlights and enlargers.

Condenser enlarger

An enlarger that uses specular light and has several lenses (condensers) to concentrate the light and increase the illumination. It produces images with more contrast and sharper detail than a diffusion enlarger.

Configuration

The choices you make when setting up a computer system to meet your needs.

Connectivity

A digital camera's connectivity defines how it can be connected to other devices (computers primarily) for either the transfer of images or remote control of the camera. Image Transfer - Early digital cameras used RS232 (serial) connections for image transfers. Most consumer grade digital cameras now feature USB connectivity, this provides a relatively fast transfer rate (up to 500 Kbyte/s) to a wide range of computer systems on the PC and Mac platforms. Manufacturers generally bundle such cameras with cables and driver software. One step up from USB is FireWire (IEEE1394) seen mostly on professional digital cameras, this offers considerably faster transfer rates but requires that your computer has a FireWire connector or you're willing to fit it out with FireWire. USB 2.0 works in the same way as the original USB standard, and even looks the same. However it uses a much higher bandwidth, up to 40 times faster than the original standard. USB 2.0 also has the advantage of being backwards compatible with existing USB technology, so all your old devices will still work from a USB 2.0-capable system.

Contact print

An image made by placing a negative in tight contact with a sheet of photographic paper or other piece of film, then exposing it to light. Although it is usually done with a photographic negative to make a positive. Contact prints can also be made positive to negative, or, with special types of film, positive or negative to negative.

Contact printer

Is an apparatus used for making contact prints. Equipment ranges from a contact printing frame to more sophisticated boxes with safe lighting.

Contact sheet ( Contact proof )

A gang sheet made by placing film directly in contact with the photographic paper. All images appear on one sheet of paper in the same size as the film.

Contamination

Traces of chemicals that are present where they don't belong, causing loss of chemical activity, staining, or other problems.

Continuous burst or capture mode

The ability to take multiple pictures in a small amount of time. Great for action shots.

Continuous shooting

Camera feature that allows a camera to take several rapid-fire exposures when the shutter button is held down. This feature is useful for shots where there is quick action and you want to take multiple shots.

Continuous shutter

A feature found on more expensive digital cameras that enables you to take several images in quick succession; the images are saved to the memory card after the multiple exposures have been taken.

Continuous tone

An image, such as a original photographic transparency or print, in which the tones or colours blend smoothly from one to another; also known as a contone.

Continuous tone ( CT ) device

A device that renders images by using tone values of different densities without applying halftone dots.

Continuous-tone image

An image containing gradient tones from black to white.

Contouring

Another name for banding or posterization.

Contrast

The difference in brightness between the lightest and darkest parts of a photographic subjects, negative, prints or slide. Contrast is affected by the subject brightness, lighting, film type degree of development, the grade and surface of the printing paper, and the type of enlarger head used.

Contrast filter

A coloured filter used on a camera to lighten or darken selected colours in a black and white photograph. For example , a green filter used to darken red flowers against green leaves.

Contrast grade

Numbers (usually 1-5) and names (soft, medium, hard, extra-hard, and ultra hard) of the contrast grades of photographic papers, to enable you to get good prints from negatives of different contrasts. Use a low-numbered or soft contrast paper with a high contrast negative to get a print that most closely resembles the original scene. Use a high-numbered or an extra-hard paper with a low-contrast negative to get a normal contrast paper.

Contrasty

Describes a scene, negative, or print with very great differences in brightness light and dark areas. Opposite: flat.

Convergence

The phenomenon in which lines that are parallel in a subject, such as the vertical lines of a building, appear nonparallel in a image .

Conversion

In computer imaging, to change a CMYK file to RGB or vice versa, or to convert one file format to another.

Convex lens

A simple lens which causes rays of light from a subject to converge and form an image.

Cool

Refers to bluish colours that by association with common objects (water, ice, and so on) give an impression of coolness.

Cool colours

Blue, purple, and brown.

Copystand scanner

An image-capture device that sits on a copystand and can be raised or lowered to get closer to or farther away from the material to be scanned.

Correction filter

A coloured filter used on a camera lens to make black and white film produce the same relative brightness perceived by the human eye. For example, a yellow filter used to darken a blue sky so it does not appear excessively light.

Correlated noise

A recognizable pattern of change in an image file, based on an increase or a decrease in the brightness of the pixels compared to what they should be. Vertical patterns of correlated noise are often called streak noise and are common problems with CCD technology. Also called periodic noise.

CP filters

Abbreviation for colour printing filters.

CPU

Central Processing Unit: A large chip which holds the " brain " of the computer.

Crop (cropping)

To trim the edges of an image, often to improve the composition. Cropping can be done by moving the camera position while viewing a scene, by adjusting the enlarger or easel during printing or by trimming the finished print.

Crossed curves

A destructive phenomenon in image processing that causes different colours to increase in density at different rates or gammas. The visual effect is a colour difference from image highlight to image shadow.

Crossed polarization

A system of using two polarizing filters, one over the light source and one between the subject and the lens. With certain materials crossed polarization causes bi-refringent effects which are exhibited as coloured bands. Used in investigations of stress areas in engineering and architectural models.

CTP

Computer-to-plate, a technology for converting digital page layout files directly to press-ready printing plates, without an intermediate film satge.

Cursor

A location marker or pointer on the monitor.

Curvature of field

Where light rays passing through a lens causing the lens to focus on a curved plane versus a flat plane. This causes out-of-focus pictures.

Custom colour printing

The art of producing, from one's knowledge of colour, a print that looks better and is more pleasing than a print that can be made purely by machine or colour management system.

Cut / paste

To cut out an image or line element, usually by masking it, and repositioning the elements (s) elsewhere.

Cyan

One of the three subtractive primary colours. It is produced by mixing equal amounts of blue and green and is the " C " in CMYK

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