PI Jargon Buster
Remember to also look at the Photo Imaging careers pages for more information about this sector.
A
A/D converter
A device that converts analogue signals to digital ones.
Aliasing
The effect that causes diagonal lines, curves or circles to be reproduced in computer graphics or bit-mapped images as jagged or stair-stepped.
Analogue
Any device that represents changing values by a continuously variable physical property, such as voltage in a circuit.
ASCII
American Standard Code for Information Interchange.
This standard code assigns numeric values to letters, numbers, punctuation marks and control characters to provide compatibility between computers and peripherals such printers.
B
Binary
Any system that uses two different states, components, conditions or conclusions. In maths, the binary system uses combinations of the digits 0 and 1 to describe all values.
Bit
Abbreviation of ‘binary digit'. The basic unit of information in a binary system of numbering where 0 equals ‘off' and 1 equals ‘on'. Bits can be grouped to make up larger units such as the byte, which equals 8 bits.
Bitmap
All digital images are made from pixels arranged in a chessboard-like grid called a bitmap, rather than lines (vectors).
Bitmap mode
The bitmap image mode can capture only two colours: black and white and is the only one you should use to scan Line Art.
Buffer
An area of memory used for the temporary storage of data.
Burst rate
An indication of the speed at which a camera can save image data then get ready to capture the next shot.
Byte
An abbreviation of ‘binary digit eight', a group of eight bits. Grouped into kilobytes (1,024 bytes), megabytes (1,048,576 bytes) or gigabytes (1,073,741,824 bytes).
C
CAD
Computer-Aided Design.
Calibration
Calibration is the setting or correcting of a measuring device or base level, usually by adjusting it to match or conform to a dependably known and unvarying measure.
CCD
Charge Coupled Device.
A solid-state imaging device that uses an array of metal oxide semiconductors (MOS) to produce an electrical output proportional to the amount of elecro-magnetic radiation (light) falling upon each pixel. Analogue signals then undergo A/D conversion to produce a digital image.
CD-R
Compact Disk Recordable is the cheapest and most cost-effective type of media for storing digital images. You need to have a CD writer to write data to these disks, but they can all be played back in a standard CD-ROM drive.
CD-ROM
Compact Disc Read-Only Memory.
CD-RW
Compact Disk Rewritable is more versatile media than CD-R.
Like a floppy disk, CD-RWs can be written to, erased then filled up again.
CIS
A Contact Image Sensor is an alternative to CCD's used in scanner technology giving higher resolution values.
CMYK
Colour reproduction system using complementary colours,
Cyan, Magenta, Yellow and blacK (K is for ‘key').
Preferred system (and the preferred form of digital files) for photomechanical printing. Books and magazines are printed using the litho process and CMYK inks.
CompactFlash
A removable memory card used in digital cameras.
Compression
Compression is a mathematical way of reducing the data size of a digital image, so you can squeeze more pictures on your removable media.
D
D/A converter
A device that will convert digital signals into analogue ones.
Digital
A term describing any system which represents values in the form of binary digits.
DOS
Disc Operating System.
DPI (scanner)
Dots per inch is a measure of resolution of a film or flatbed scanner.
DPI (printer)
DPI also describes the maximum number of separate droplets an inkjet printer can spray onto media.
DPI (image file)
The pixels in a digital image can be made smaller or larger by altering their spatial resolution. Sometimes referred to as pixels per inch or ppi.
DPOF
Digital Print Order Format is a recent set of universal standards allowing you to specify print out options directly from your camera.
DVD
An abbreviation of 'digital versatile disc' or ‘digital video disc'.
Usual capacity 4.7 Gb.
E
Exposure
the amount of light allowed to fall onto a film or digital chip. It is the product of time (the shutter speed) and intensity (the aperture or f-number). In any given situation there is an ideal ‘exposure' which will make a technically good picture, and which depends on subject brightness, chip sensitivity (ISO equivalent) and the purpose of the shot.
F
File Format
Digital images can be created and saved in many different file formats such as JPEG, TIFF, PSD. Formats are designed to let you to package images for future purposes, like email, print out and for your web page. Not to be confused with disk formatting.
Firewire
Firewire or IEEE 1394, a computer interface for the rapid transfer of data
FlashPath
A FlashPath adaptor is a 3.5 floppy disk which has been modified to accept SmartMedia memory cards and is used to transferring digital camera data to your PC through it's floppy disk drive.
FlashPix
The FlashPix file format is a Kodak/HP invention used to create digital camera files. This can only be opened in a compatible application.
G
GIF
The Graphics Interchange Format file is used to save graphics and logos for use in web pages. GIFs have 256 colours or less and can have a tiny file size.
Gigabyte
A gigabyte is 1024 megabytes
Greyscale mode
The greyscale mode is used to capture black and white images. There are 256 steps from black to white in a greyscale image, just enough to prevent banding to the human eye.
H
High Resolution
High-res images are generally made with a million or more pixels and are used to make high quality print outs. High-res images can demand lots of storage space.
Hotshoe
A fitting, often situated on top of the pentaprism of DSLR cameras, which allows for flashguns to be attached to, and controlled by, the camera.
HSB
Hue, Saturation and Brightness.
I
IBM Microdrive
A high capacity removable media used in digital cameras, available up to 1 Gigabyte capacity. Like a PCMCIA cards, Microdrives are like mini hard drives, and as such are susceptible to physical damage
Image processing
Computer-based processing of the digital image. Examples of image-processing software include Adobe Photoshop and Apple Aperture programmes.
Interpolation
All digital images can be enlarged, or interpolated by introducing new pixels to the bitmap grid. The new information introduced is the result of the programme's intelligent prediction of probabilities.
ISO
International Standards Organisation, based in Geneva.
Supplanted ASA (American Standards Association) as the preferred standards body for photography towards the end of the 20th century.
J
JPEG
JPEG is an acronym for Joint Photographic Experts Group and is a universal kind of file format used for compressing images. Most digital cameras save images as JPEG files to make more efficient use of limited capacity memory cards.
Jumpshot cable
Jumpshot is a low-cost high performance USB digital card reader made by Lexar.
L
LCD
Liquid Crystal Display, often employed in portable computer screens.
The screen image is formed by employing an electric current to align crystals in a liquid.
LED
Light Emitting Diode.
Line Art
This is a type of artwork created with only one colour, e.g. black text or line.
Lithium Battery
A type of rechargeable battery used in digital cameras.
Low-pass filter
Also known as a 'Smoothing Filter', used to remove image noise and speckle.
Low Resolution
Low-res images have a small file size and produce poor quality print-outs and are only suitable for web page display.
LUT
Look-Up Table.
A collection of data values.
M
Megabyte
One megabyte is equal to 1024 kilobytes. Unlike word processing documents high quality digital images are constructed from millions of tiny instructions, making storage space problematic.
Megapixel
A megapixel is another term for a million pixels and is used to describe the capability of a digital camera.
Memory Stick
A removable memory card launched by Sony in 1998 and used primarily in Sony digital cameras and video cameras
Menu
A list of options or commands found on a computer program or digital camera.
N
Nicads
Nickel Cadmiums are a type of rechargeable batteries used in digital cameras.
Noise
Used in digital photography to describe image degradation (usually at high ISO-equivalent speeds or in cases of considerable under-exposure) similar to coarse graininess in film.
O
OCR
Optical Character Recognition.
A function of most scanner software by which text or diagrams can be scanned into the computer to give the digital equivalent of printed text or a ‘line' diagram.
Optical resolution
Sometimes called true resolution, this refers to the uninterpolated pixel dimensions of an image.
P
Parallax
Parallax error occurs in cameras fitted with optical viewfinders set to one side or above the lens. When used to close focus, what you see through the viewfinder will be different from the image captured by the lens.
Parallel
This type of connection is mainly associated with older printers and scanners. The rate of data transfer through a parallel connection is slowest of all.
PCI Slot
The Peripheral Component Interface slots are found in better computers for adding and upgrading your system with new ports like SCSI, USB or Firewire.
PCMCIA
Known as a PC card, this is a high capacity removable media designed for use in professional digital cameras. Unlike solid state SmartMedia and Compact Flash cards, PC cards have moving internal parts like mini hard disks. Most good quality laptops have a PCMCIA port for reading cards directly.
Pixel
The word pixel is derived from PICture ELement and is the smallest component of a digital image.
Pixellation
When a digital print is made from a low-res image, fine details appear pixellated because not enough pixels were used to describe complex shapes.
Plug-in
A plug-in is a piece of software that adds extra functions to an application like Adobe Photoshop.
R
RAM
Random Access Memory is the part of the computer that stores data during work in progress, helping run applications and keep large images open. Differing from ROM (read only memory) in that the contents of the chip(s) are easily changed. The content of RAM memory is cleared as soon as power running the computer is switched off.
Recovery time
Digital cameras have varying degrees of delay before the next shot can be captured, caused by sending image data to the memory card.
Removable memory cards
Digital cameras have removable memory cards, which are available in different megabyte capacities, such as 8, 16 and 32Mb. Bigger cards are more expensive, but allow you to store more pictures before transferring to a computer.
Resolution
The term resolution refers to both image quality and pixel quantity. Traditionally, the measure of the ability of an imaging system to separate individual components of an image. With digital cameras, resolution is expressed in terms of the number of pixels within a CCD array, in printing as the number of dots per inch (dpi).
RGB mode
The RGB mode stands for Red, Green and Blue and is the standard mode for colour images. Each separate colour is has its own 256 step range. (see CMYK for comparison)
ROM
Read Only Memory.
Differing from RAM in that the contents of the chip are unchangeable. Most personal computers contain a small amount of ROM that stores critical programs such as the program that boots the computer. In addition, ROMs are used extensively in electronic equipment such as calculators, laser printers and digital cameras.
S
SCSI
Small Computer Systems Interface is an older type of connector used for attaching scanners and other peripherals to your computer.
Serial
A Serial interface, or connector, is used for attaching printers and digital cameras to your computer. Serial data transfer is much slower than SCSI and USB.
SmartMedia
SmartMedia memory cards are the thinner type of removable memory card, sold in various sizes up to 128mb.
T
Terabyte
Equal to 1000 gigabytes, or 1,099,511,627,776 bytes.
Thumbnail
Low-resolution digital image used for library or viewing purposes.
TIFF
The Tagged Image File Format is a universal standard image file format used in desktop publishing.
TWAIN
Toolkit Without an Interesting Name is the software equivalent of a travel plug adaptor, allowing TWAIN compliant devices like scanners and digital cameras to communicate with applications like Photoshop.
U
USB
A Universal Serial Bus is a type of computer to peripheral connector allowing plug and play switching. Older systems like SCSI could only be plugged in when a computer was switched off.
W
White balance
A control, available in the menu of all high-quality digital cameras and in some computer-based applications, allowing the neutralisation of potential colour casts caused by different light sources. Can also be used to introduce an imbalance in the overall colour of an image for ‘creative' purposes.
With thanks to John Bigglestone and Tim Daly.
