Baffled by the terminology? In need of clarification? Our glossary explains all .....

Please click on the first letter of the word you'd like to look-up A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A Alpha Channel An extra 8-bit, greyscale channel in an image - used for creating Masks to isolate part of an image. Aperture Variable opening that controls the amount of light that passes through the lens. Measured in f stops, where the higher the 'f number' the smaller the physical aperture. Wide apertures (such as f2.8) let lots of light in and give limited depth-of-field, whereas narrow apertures (such as f22) give greater depth-of-field but let much less light through. Analogue Continuously variable. Anti-Aliasing Smoothing the jaggy edges (aliasing) of selection or paint tools in digital imaging applications. Artefact Any defect or flaw in a digital image.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z B Bit A binary digit, basic digital quantity representing either 1 or 0. The smallest unit of computer information. Blooming 'streaks' or 'halos' seen around bright reflections or light sources in digital pictures. Caused by leakage of electrical charge between CCD elements due to gross over exposure. Buffer RAM Fast memory chip in a digital camera. Buffer RAM is used to store images whilst they are recorded onto the (much slower) removable media card. This allows cameras to take a number of shots in rapid succession without waiting for the previous image(s) to be written to the card. BMP A file format for bitmapped files used on the Windows platform. Byte Standard computer file size measurement: contains eight bits. Other common units include Kilobyte (KB; 1024 bytes), Megabyte (MB; 1024K) and Gigabyte (GB; 1024 MB). Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z C Calibration The process of adjusting a device - scanner, screen, printer etc. so it captures, displays or outputs colour in an accurate and consistent way. CCD A Charged Coupled Device (CCD) converts light into electrical current.The digital camera equivalent of film. CD-R Recordable CD, useful archiving system for digital photography. CD-Rs can only be written once and not erased. Also available are rewritable disks/drives (CD-RW) which are more expensive but can be erased and reused. CD ROM A non-rewritable digital storage Compact Disk used to provide software. Cloning A feature of many image-editing software programs where part of an image can be duplicated over another part. Used to seamlessly 'paint out' blemishes and for special effects. Colour Bit Depth The number of bits used to represent each pixel in an image; the higher the bit depth the more colours appear in the image: 1-bit colour: black & white image with no greys or colours 8-bit colour: 256 colours or greys 24-bit colour: 16.7 million colours ('photorealistic' colour). CompactFlash Type of digital camera removable storage media. Compression The 'squashing' of data to reduce file size for storage or to reduce transmission time. Compression can be 'lossy' (such as JPEG) or 'lossless' (such as TIFF LZW). Greater reduction is possible with lossy compression than with lossless schemes. Contrast The range of tones in an image between highlight and shadow. CPU (Central Processing Unit) The 'brains'; of the computer; carries out all the instructions and calculations needed for the computer to work. Cropping tool A tool found in image-editing software. Allows you to trim an image.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z D Data The generic name for any information used by a computer. Default The standard setting for a software tool or command, used if the settings are not changed by the user. Depth-of-field The area in front of and behind the focused point that is sharp. A shallow depth-of-field is used in portraits to provide a soft backdrop, whilst a greater depth-of-field is useful for landscapes to ensure everything from the foreground to the background is in focus. Shorter (wideangle) lenses and smaller apertures increase depth-of-field. Dialog Box A window in a computer application where the user can enter options or change settings. Digital Zoom Camera feature involving enlarging the central part of an image to give a similar effect to a telephoto lens (in fact it is simply a crop). Usually results in a drop in image quality. Disk (or Disc) Term used to describe any magnetic or optical storage media such as floppies, CDs,zips and hard drives. Dithering A method for simulating many colours or shades of grey with only a few. Download The transfer of files or other information from one piece of computer equipment to another (as when transferring pictures from a camera). Dpi (Dots per inch) A measurement of the resolution of a printer or video monitor. (See also Ppi) DPOF (Digital Print Order Format) A new system which allows digital camera owners to select images and quantities for printing in-camera. Also supported by some direct connection printers and high street digital printing shops. Driver A software utility designed to tell a computer how to operate an external device (i.e a printer). top   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z E Exposure The amount of light falling on to the CCD of a digital camera. Exposure is determined by the combination of shutter speed (duration) and aperture (intensity). In most digital cameras the exposure is determined automatically. Exposure Compensation The ability to increase or decrease the exposure set by the camera's automatic system. Usually measured as + or - 'EV' (exposure values). The three images below show (from left) -1.5, 0 and +1.5 EV;  Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z F F Stop/F Number See Aperture. Feathered Edge Soft edge to a mask or selection. Allows seamless montage effects. File Word used in computers to describe a single document (i.e a digital photograph) stored on a disk. Filter Photo-editing software function that alters the appearance of the image being worked on, much like the physical filters that can be put on the front of SLR camera lenses. Fixed (non Zoom) Lens A lens with a fixed focal length. Also called a 'prime' lens. On digital cameras fixed lenses are usually wideangle. Focal Length The attribute that determines the magnification and field-of-view of a lens. (See Telephoto, Wideangle and Zoom). Focus Adjusting a lens so that the subject is recorded as a sharp image on the CCD. There are three types of focus system used in digital cameras; fixed focus (focus-free), autofocus and manual focus. Flash Memory A type of fast memory chip that remembers all its data even when the power is turned off. See Removable Media, CompactFlash, PCMCIA and SmartMedia. FlashPath Adapter for SmartMedia cards which allows them to be read using a standard 3.5-inch floppy drive. Fringe A (usually) unwanted border of extra pixels around a selection caused by the lack of a hard edge. Can also describe an unwanted artefact in digital camera pictures, caused by lens defects or problems with the CCD itself.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z G GIF A graphic file format developed for exchange of image files (only supports 256 colours). Greyscale What photographers would call a black & white image, contains a range of grey tones as well as black and white. top   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z H Hard Disk (aka Hard Drive) A fast and cheap form of digital storage (usually refers to a computer's internal disk). Hue/Saturation An RGB image can also be defined by Hue, Saturation and Brightness, where Hue is the colour and Saturation the 'strength'. Hue/Saturation controls are useful for altering colours without effecting overall brightness or contrast.     Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z I Icon A small graphic symbol on a computer screen that can be pointed and clicked on with a mouse and represents a file, disk, application or command. Infinity The farthest possible distance a lens can be focused on. Internal Storage Some digital cameras have some built-in memory (although it has recently been replaced by Removable Media on most models). Interpolation Increasing the number of pixels in an image or filling in missing colour information by averaging the values of neighbouring pixels (basically using an educated guess). This 'resampling' cannot add detail or information.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z J Jaggies The jagged stepped effect often seen in images whose resolutions are so low that individual pixels are visible. JPEG A file format that stores digital photographs in a very space efficient way. Used by virtually all digital cameras, JPEG uses a form of 'lossy' compression to reduce file sizes at the expense of fine image detail. The level of compression (and thus the loss of quality) can be varied, and this forms the basis of digital camera quality settings.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z L Lasso A selection tool used to draw a freehand selection around an area of an image. Magnetic Lasso tools automatically 'snap' to edges in the image as you draw. LCD Monitor A small colour screen found on many digital cameras that allows previewing/ reviewing of images as they are taken. Lossy A type of compression that involves some loss of data, and thus some degradation of the image. JPEG is a common lossy system. Lossless File compression that involves no loss of data and therefore no loss in quality. LZW is a lossless compression system used in TIFF files. Lossless compression produces much lower space savings than lossy.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z M Macro Description used to indicate a lens that can focus closer than normal (usually nearer than about 30cm). Manual Override The ability to alter the automatic setting on a camera (exposure or focus). Mask In digital imaging an 8-bit overlay which isolates areas of an image prior to processing. The mask is used to define an area of an image to which an effect will NOT be applied by 'masking out' those areas and thus protecting them from change. The areas outside the mask (i.e those not protected) are called the selection. Marquee Outline of dots created by an image-editing program to show an area selected for manipulation, masking or cropping. Most applications also call their basic selection tools (rectangles and squares) marquee tools. Modem A device that allows computers to communicate over long distance telephone lines. Moiré Ugly patterns appearing in scans of printed materials. Cannot easily be remedied although most flatbed scanners offer a 'descreen' function. Morphing A special effect common in films where one image smoothly changes into another.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z N Network Two or more computers and peripherals that are connected (by direct cable links or over phone lines using modems).   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z O Optical Viewfinder A viewfinder system that shows a similar view to that seen by the camera lens (as on 35mm compact cameras). Useful because it uses no power, but can cause parallax and focus errors.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z P Parallax Error Mis-framed photographs (especially close-ups) caused by the different viewpoints of the lens and the optical viewfinder. PC Card (also known as PCMCIA card) A once popular standard for removable cards used in some digital cameras and laptop computers. PC cards can contain hard disks, modems or Flash Memory. They are being replaced by smaller and cheaper mini flash cards (these often have adapters to fit them in PC card readers) Peripheral Any item that connects to a computer (i.e printer, scanner, camera). Photosite A single photosensitive element in a CCD which translates to one pixel in the resultant image. Also known as a CCD Element. Photoshop Plug-In A small piece of software that adds extra features or functions to Adobe Photoshop or other compatible applications. Most common uses are to add new special effects (filters) or to allow direct access to scanners/digital cameras from inside Photoshop. Power-Up Time Important measure of a digital camera's speed of operation; how long it takes from turning the unit on until it is ready to take the first picture. Ppi Pixels/points per inch. A measure of the resolution of scanners, digital images and printers. top   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Q Quick Mask A special mode in Adobe Photoshop that allows a mask to be viewed as a colour overlay on top of the image. This mask can then be edited using the standard paint and selection tools. Other applications offer similar 'paint on mask' tools.    Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z R RAM Random Access Memory. The computer memory where the CPU stores software, and other data currently being used. A large amount of RAM usually offers faster manipulation of images. Recovery Time The delay during which a new picture cannot be taken on a digital camera while waiting for the picture just taken to be saved. Can be as long as 10 seconds (although this is rapidly improving). Refresh Rate In digital camera terms how many times per second the display on the LCD preview monitor is updated. A refresh rate of under about 15 fps (frames per second) will look 'jerky'. Removable Media Small memory chips which store the captured images. The two main formats are CompactFlash and SmartMedia - CompactFlash cards offer higher capacities but SmartMedia cards are smaller (and slightly cheaper). Other types of removable media used include PCMCIA, Multimedia/Secure Digital (MM/SD) and Sony's Memory Stick. Resample To change the number of pixels in an image. Upsampling uses interpolation to increase the number of pixels, Downsampling throws away pixels to reduce the size. Resize Changing the resolution or physical size of an image without changing the number of pixels. For example a 2x2-inch image at 300 dpi becomes a 4x4-inch image at 150 dpi. Often confused with Resampling. RGB Red, Green and Blue. TVs, monitors and digital cameras use a mix of R,G & B to represent all the colours in an image. ROM Read Only Memory. ROM is fixed memory that can be read, but not written. Inside a computer or peripheral it contains the basic code that allows the CPU to work. Rubber Stamp See Cloning.     Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z S Saturation The amount of grey in a colour. More grey means lower saturation. See also Hue/Saturation. Selection In image-editing, an area of an image isolated before an effect is applied. Selections are the areas left uncovered by a mask. Common selection tools include the lasso, marquee and magic wand. Serial Transfer Connecting a digital camera to a computer via the serial port (also known as the COM port on PCs or Printer/Modem port on Apple Macs) in order to download images. Quite slow. Shutter Speed The time for which the CCD or film is exposed during an exposure. High shutter speeds (hundredths or thousandths of a second) prevent Camera Shake and can freeze motion in photos. Slow (long) shutter speeds allow exposures in low light and can be used for special blur effects. Shutter Lag or Delay The brief delay between pressing the shutter and a picture being taken. SmartMedia Type of digital camera removable media used by, amongst others, Fuji and Olympus. Subject Modes/Scene Modes Special fully automatic exposure modes designed to use the optimum settings for specific subjects such as portraits, landscapes or sports.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z T Telephoto Lens Lens that has the effect of making subjects seem closer than they actually are. Thumbnail A small, low-resolution version of a larger image file that is used for quick identification and for displaying many images on a single screen. TIFF The standard file format for high-resolution bitmapped graphics. TWAIN Protocol for exchanging information between applications and devices such as digital cameras.     Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z U Unsharp Masking A software feature that selectively sharpens a digital image in areas of high contrast whilst having little effect on areas of solid colour. The effect is to increase the apparent detail and sharpness. USB (Universal Serial Bus); type of connector for attaching peripherals such as mice, keyboards, scanners, printers and disk drives. Offers faster data transfer and easier (plug 'n' play) connections than PC parallel port or Mac serial ports. Works with Windows 98/Mac OS 8.5 or above.   Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z V Video Output Ability to display digital camera images on a standard TV or record images on videotape.    Back to the top A B C D E F G H I J K L M N O P Q R S T U V W X Y Z WXYZ White Balance In digital camera terms, an adjustment to ensure that colours are captured accurately (without any 'colour cast') whatever the lighting used. This can be set automatically, using presets for different lighting types or measured manually, depending on the camera model. Wideangle Lens A lens of short focal length giving a wide angle view, allowing more of a scene to be fitted into a photograph. Zip (i) Popular removable storage disks for computers. Drives and disks are available in 100MB and 250MB versions. (ii) Type of compressed file (.zip) popular for sending data online