The process of setting equipment to a standard measure.

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.

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

(Charge-Coupled Device) A light sensitive electronic chip used by scanners to measure light.

CD-Recordable: a compact disc that holds either 650 or 700 MB of digital information, including digital photos. Creating one is commonly referred to as burning a CD. A CD-R disc can only be written to once, and is an ideal storage medium for original digital photos.

CD-Rewritable: similar in virtually all respects to a CD-R, except that a CD-RW disc can be written and erased many times. This makes them best suited to many backup tasks, but not for long term storage of original digital photos.

One greyscale scan or one of the three RGB components making up a colour scan.

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.

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.

"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

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.

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

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

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

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.

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.

(Colour Look-Up Table) A collection of most-often-used colours stored in a file or the System.

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.

Complementary Metal-Oxide Semiconductor: one of the two main types of image sensors used in digital cameras. Its basic function is the same as that of a CCD. CMOS sensors are currently found in only a handful of digital cameras.

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

(cyan, magenta, yellow, black) The subtractive primaries, also known as the process colours, used for colour printing.

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.

The number of bits assigned to each pixel in the image and the number of colors that can be created from those bits. Traue Collor uses 24 bits per pixel to render 16 million colors.

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.

"(1) 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. (2) Referring to colour films, they are balanced in manufacture for exposure to light of a certain colour quality

"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

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.

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

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

"A feature found on most inkjet printers that controls the brightness of an image by varying the amount of ink applied to the page

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

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.

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

"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."

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

Dividing a colour image into its four CMYK components for printing. (Also refers to the C, M, Y or K film negative from which printing plates are made.)

"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."

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

"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

(comprehensive) A test print used to evaluate layout and design.

A common type of digital camera memory card, about the size of a matchbook. There are two types of cards, Type I and Type II. They vary only in their thickness, with Type I being slightly thinner. A CompactFlash memory card can contain either flash memory or a miniature hard drive. The flash memory type is more prevalent.

The process of decreasing a file size.

A file compression scheme that makes a file smaller without degrading the image.

A file compression scheme that reduces the size of a file but degrades it in the process so it can't be restored to its original quality.

Look for a digital camcorder with a FireWire (IEEE 1394) connection, also called i.LINK and DV In/Out terminal. FireWire lets you import video into your PC fast and easy. Video can transfer through an IEEE 1394 at up to 400 Mbps, much faster than a standard port. The camcorder connects right to the PC for easy transfer. If your computer has an IEEE 1394 port, you can transfer, edit and save video from your IEEE 1394-equipped camcorder. For those computers without an IEEE 1394, you can buy PCI card that will add this connection to your PC.

The range between the darkest and lightest areas in an image.