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Glossary

A


Anti-aliasing
The process of reducing stair-stepping by smoothing edges where individual pixels are visible.

APS (Advanced Photo System)
An abbreviation for Advanced Photo System. It is a film cartridge system that magnetically records all picture data for each frame of film. This data is then used by the lab to provide you with pictures and services that can't be found with traditional film cameras.

Artifact
An undesirable degradation of an electronic image. Usually occurs during the electronic capture, manipulation, or output of an image.

Aspect Ratio
The ratio of horizontal to vertical dimensions of an image. i.e. 35mm slide frame is 3:2, TV 4:3, 4X5 film 5:4.

 

B


Banding
An artifact of color gradation in computer imaging, when graduated colors break into larger blocks of a single color, reducing the "smooth" look of a proper gradation.

BMP (Bitmap)
An image made up of dots, or pixels. Refers to a raster image, in which the image consists of rows or pixels rather than vector coordinates.A method of describing an array or map of bits (smallest piece of binary information used by a computer) within a rectangular grid of pixels or dots.

Brightness
The lightness of a colour or tone, regardless of hue or saturation.

 

C

C41 Process
C41 is the standard process for all types of general use colour negative film (including some black and white negative films, namely Ilford?s XP2 and Kodak?s T400CN).

Calibration
The act of adjusting the color 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 color of one device to some established standard.

Card Reader
Term used for a device that can read the information from a Memory card.

CCD-Charged Coupled Device
A charged coupled device (CCD) converts light into proportional (analog) electrical current. The two main types of CCDs are linear arrays used in flatbed scanners, digital copiers, and graphic arts scanners, and area arrays used in camcorders, still-video cameras, digital cameras, and fast scanners.

CD
The abbreviation for compact disc, a laser-encoded plastic medium designed to store a large amount of data. A variety of CD formats are available for use by computers.

CD drive
A drive mechanism for recording or playing CDs.

CD-R eWritable Media
A product on which users can record digital files for permanent or temporary storage. Because it allows multiple recordings, users can erase and rewrite as often as required.

CD-ROM (Compact Disc - Read-Only)
A non-rewritable CD used by a computer as a storage medium for data.

Channel
One piece of information stored with an image. RGB, for example, have three channels - red, green and blue. CMYK has four - cyan, magenta, Yellow and Black.

Clip Test
Clip testing a roll of film is a process whereby a short length of film is cut from the beginning or end of a roll of film (only possible with 35mm and 120/220mm film) and processed separately at a nominated speed to check for overall exposure, before processing the balance of the film. Clients may either assess their own film, or ask lab staff to do so. Assessing a clients film naturally involves a high degree of responsibility and is done by senior, experienced staff and often involves a second or third opinion.
Clip tests are also occasionally referred to as Snip Tests.

CMYK (Cyan, Magenta,Yellow, Key (Black)
The primary colours of the halftone printing process.

Colour Cast
An overall colour inbalance in an image.

Colour Gamut
The limited range of colours that can be reproduced by a device or set of colourants. Colour gamuts are device specific.

Colorimeter
An instrument used to read or specify colour by measuring the amount of light transmitted or reflected in tristimulus values. 

Colour Management System
A software system that ensures colour consistency and repeatability across all devices in a produsction workflow.

ColorSync
The macintosh operating system's colour management resource for passing device-specific colour profiles.

Colour Space
A mathematical model that is used to describe colour in which each colour is represented by a point in space. Each colour is defined in terms of three numbers and plotted as a point in space relative to three axes. RGB and CMYK are examples of colour spaces.

Colour Temperature
A measurement of the colour of light in degrees Kelvin. The lower the temperature the yellower the light appears. The high temperatures appear bluer. 6500K represents a neautral grey.

Contrast
A variation between the lightest and darkest areas in an image.

Compact Flash
A type of storage card used in digital cameras to store images captured by the camera. The Compact Flash can then be erased when the images have been transferred and reused. It also fits into a PCMCIA adapter eliminating the need to connect the camera to some computer systems.

Compression
The reduction of data to reduce file size for storage. Compression can be "lossy" (such as JPEG) or "lossless" (such as TIFF LZW). Greater reduction is possible with lossy compression but image quality is therefore reduced.

Continuous Tone
Where an image appears consistent and uninterrupted. Each pixel in a continuous tone image file uses at least one byte each for its red, green, and blue values. This permits 256 density levels per color or more than 16 million mixture colors.

Contrast
A measure of rate of change of brightness in an image. High contrast implies dark blacks and bright whites. Medium contrast implies a good spread from black to white. Low contrast implies small values from black to white.

CRT (Cathode-Ray Tube)
The vacuum tube that is used as a display screen in computer monitors and television sets.
 

D

Dip and Dunk
A trade term depicting the use of film processors which transport film on racks, dipping them into the respective chemical solutions which brings about the development of the film. This process ensures minimal machine contact with the photographic film and removes the risk of scratches, as well as superb consistency of process.

DPI (dots per inch)
A measure of printer resolution that indicates how many dots of colour an output device can place in one square inch.

Drift
Small changes that happen to a device over time.

Duplicate Transparency
This is a transparency copy off another transparency.

 

E

E6 Process
E6 is the standard process for all types of colour transparency/slide film (with the exception of Kodak Kodachromec film and Agfa Scalac black & white transparency film).

EPS (Encapsulated PostScript)
A graphic file format to allow exchange of PostScript graphic files (image information) between application programs.

 

F

FTP (File Transfer Protocol)
A client-server protocol that allows file transfer over a TCP/IP network.

File Format 
Files can be saved in a range of file formats for different purposes. Some common file formats include TIFF, JPEG, and EPS.

Film Recorder
A device that is used to record a digital image onto photographic film.

Firewire
A very fast external bus that supports data transfer rates of up to 400 Mbps.

FTP (File Transfer Protocol
An abbreviation for File Transfer Protocol and is a universal format for transferring files on the Internet.

Flash Memory
A type of memory chip that can retain data after the system has been turned off. Its advantage is that digital cameras with flash memory can have batteries go "dead" and yet retain image data.

 

G

Gamma
A number representing the gamma curve of a device. A gamma of 1.0 represents a linear device. Gamma is associated with contrast because increasing the gamma increases the contrast in shadows and midtones which decreases the contrast in highlights.

Gamut
A limited range of colours reproducible by a given device.

Gray Balance
The balance between colourants required to produce neutral grays with no colour bias.

Gigabyte (GB)
A measure of computer memory or disk space consisting of about one thousand million bytes (a thousand megabytes). The actual value is 1,073,741,824 bytes (1024 megabytes).

Gray Scale
A term used to describe an image containing shades of gray as well as black and white.

 

H

Halftone Image
An image reproduced through a special screen made up of dots of various sizes to simulate shades of gray in a photograph. Typically used for newspaper or magazine reproduction of images.

Hardware
The 'nuts and bolts' of the computer, that includes the monitor, CPU, printers, disc drives, and etc.

HDTV
High Definition Television. New video "standard" that will resolve 1,125 lines in the United States instead of the traditional 525 lines of the NTSC standard. In Europe and the Far East, the number of scan lines varies.

Highlight
The lightest or brightest points in an image.

Hue
A term used to describe the entire range of colors of the spectrum; hue is the component that determines just what color you are using. In gradients, when you use a color model in which hue is a component, you can create rainbow effects.

Histogram
A bar graph analysis tool that can be used to identify contrast and dynamic range image problems. Histograms are found in most software programs that are used to manipulate digital images.

 

I

ICC (International Colour Consortium)
A committee formed in 1993 to establish standards for electronic colour publishing.

ICC Profile
Profile conforming to International Colour Consortium profile format standards.

Image Resolution
The number of pixels per unit length of image. For example, pixels per inch, pixels per millimeter, or pixels wide.

Import
The process of bringing data into a document from another computer, program, type of file format, or device.

Ink-Jet Printer
An inexpensive alternative to a laser printer, an ink-jet printer forms text and images out of dots created by jets of ink.Color ink-jets support many different media sizes and output resolutions.

Interpolation
A method of increasing image resolution artificially. A digital camera relies on its internal hardware components to capture images. The hardware typically has a maximum image resolution-for instance, 1,280 x 1,024 pixels-that it can achieve. That resolution is known as the camera's optical resolution. Some cameras, however, use built-in software coding to capture images with resolution than exceeds the camera's hardware limitations. That resolution is known as the camera's interpolated resolution. Interpolation creates new pixels from those that exist and inserts them in-between the existing pixels to increase the image's overall resolution. Though interpolation can improve picture quality, interpolated images can tend to look fuzzy or pixelated when enlarged.

ISDN
(Integrated Services Digital Network) - a special digital phone line that your phone company can usually supply (at a higher expense than a regular phone line). It has a higher bandwidth than POTS.

 

J

JPEG or JPG (Joint Photographic Experts Group)
A standard image compression method using a cascade of compression modes that can achieve compression ratios as high as 100:1
 

K

Kilobyte (KB)
An amount of computer memory, disk space, or document size consisting of approximately one thousand bytes. Actual value is 1024 bytes.

Kelvin
A system of absolute temperature. For our purposes, the scale is used for the expressing colour temperature of the white point of the light source in a computer monitor, and the colour temperature of the light source used to view images.
 

L

Large Format
Any image greater than 6cm x 9cm, up to and including 20cm x 25cm (8? x 10?).

LCD (Liquid-Crystal Display) 
The display screen used in laptop and imac computers.

Lightness 
The variation of a hue along a range from white to black.
 

M

MB (Megabyte)
A measure of computer data (equal to 1,048,576 bytes).

Medium Format
Any image larger than a standard 35mm (24x36mm) image, up to and including 6cm x 9cm.

Midtone 
The middle range of tones in an image.

Multimedia
A synthesis of digital media types combining texts, graphics, audio animation and video in an interactive format.

Multisession CD-ROM
Describes the CD-ROM format that allows information to be recorded incrementally in different recording sessions.

 

N

Neutral
An area of colour containing no bias: white, gray or black.

 

P

PC / Mac
Terms generally used to refer to computers running on Microsoft Windows and Apple Macintosh operating systems.

Phosphor
A substance which coats the inside of computer monitors which glows when struck by certain wavelengths of radiation.

Pixel
The smallest element of a digital image where brightness or colour values have been measured.

PostScript
A standard page description language in desktop publishing that describes the appearance of text, graphical shapes and images as printed or displayed pages in a device independent way.

Profile
A file containing data which describes how a device handles or distorts colours. Profiles are used by a colour management application to correct the passage of colour through a device.
 

R

Resolution
The amount of detail in spatial or colour variation that can be identified in an image.

RIP
The method used to convert a Vector or Page Layout Program file into a bitmap or Photoshop compatible file.

RGB (Red, Green, Blue)
A colour model based on the three additive primary colours of light used in colour reproduction - red (R), green (G) and blue (B). Monitors, scanners and photographic outputs such as the LED, Lightjet and film recorders are generally RGB devices. RGB is relative colour space. RGB is the primary colours of light from which all other colour can be obtained.

 

S

Shadow
The darkest areas in an image.

 

T

Tonal Range
The maximum range of visible tones in an image.

TIF or TIFF (Tagged Image File Format)
A platform independent image file format specifically designed for scanned images.

 

U

USB (Universal Serial Bus)
USB is a multi-platform industry standard for connecting computers and peripherals.

 

W

White Balance
The balance between colourants required to produce neutral gray with no colour bias.

White Point
The chromaticity of a light source, often described by refering to its chromaticity coordinates or the colour temperature of the light source.

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