Digital Travel Photography: Glossary

Text: 2014© Garry Benson
Tracey Benson

Garry about to be consumed by Clavis the crocodile

Garry about to be consumed by Clavis the crocodile

Different specialties have different jargon. For example, most academics know that Clavis is another term for a Glossary so I’m just being a smart ass by using it. Common usage means that the word ‘Vegan’ rarely refers to the ‘someone from Vega, Norway’ but after watching the ‘Vikings’ I wouldn’t want to upset any of them. Besides, as Tracey has pointed out, the Bensons are from Drammen in Norway.

Enough weasel words (a personal favourite). The following is a fairly complete Clavis or Glossary of terms used in Digital Photography. Of course, what’s used today will change – the beauty of language…

[A-I] [J-Q] [R-Z]

Digital photography glossary – A to I
[Top] [A-I] [J-Q] [R-Z]

  • 24-bit image This type of digital image has pixels that are allocated 24 bits of storage (usually with 8 bits for red, 8 for blue, and 8 for green), allowing representation of 256 by 256 by 256 (or more than 16 million) different colour combinations.
  • 8-bit image This is a digital image composed of as many as 256 possible colours or shades of grey.
  • Acquire The act of transferring an image from a digital camera to a computer or of importing it from another source into a program, such as Adobe Photoshop
  • Adaptive palette This is a set of colours selected to represent, as closely as possible, the colors in the original source image.
  • AF sensor The sensor used to detect and help correct the focus in cameras equipped with an autofocus function.
  • Algorithm A formula or set of steps for solving a particular problem.
  • Ambient A term used to describe the lighting or illumination in a scene that does not originate from any specific light source, direction, or object in the scene.
  • Angle of view The width of the area a lens can see; measured in degrees.
  • Aperture The opening behind a camera lens through which light passes to make a photographic exposure. The range of sizes to which the aperture can be set is described by the f-stop numbers (for example, f/1.8 through f/22). Lower numbers indicate larger aperture sizes; the larger the aperture, the more light enters the camera.
  • Artifact Misinterpreted information from a JPEG or a similarly compressed image; includes defects that appear in an image as colour flaws or skewed lines.
  • Artifical light Light from a man-made source, usually restricted to studio photo lamps and domestic lighting.
  • ASA See Speed
  • Aspect ratio This is the ratio of height to width of an image, computer screen, LCD screen, television, or other medium. Images will become distorted if they are forced into a different aspect ratio during enlargement, reduction, or transfers.
  • Autofocus Camera feature that uses an infrared (IR) beam or sonar to set its focus.
  • Available light The light present in an area without the addition of a strobe or a floodlight.
  • Backlighting Illumination of the subject of a photo from behind using either artificial or natural light. Also referred to as Contre Jour.
  • Bit Short for binary digit, which is a computer value of zero or one, on or off; this is the most basic language used by computers.
  • Bit depth Refers to the colour or grayscale of an individual pixel. A pixel with 8 bits per colour produces a 24-bit image; 8 bits multiplied by three colours — red, green, and blue — equals 24 bits.CCDs are colored in a pixel-by-pixel method, using the following guidelines:
    • 32-bit colour (true colour) contains billions of colours; suitable only for high-end use
    • 24-bit colour (true colour) contains 16.7 million colours
    • 16-bit colour (high colour) has 32,000 colours; the accepted standard for Macintosh
    • 8-bit colour has 256 colours; this is the basic setting for Windows
    • 8-bit grayscale has 256 shades of grey
    • 4-bit is 64 colours or greys
    • 2-bit is black and white
  • Bitmap A means of describing and displaying a graphic image onscreen, pixel by pixel.
  • Black point This is the colour that produces colour values of 0, 0, 0 for each of the RGB components when scanned or digitised. Normally, the black point is 0 percent neutral reflectance or transmittance.
  • Bleed Refers to printing that extends beyond the edge of a page so that the ink meets the edge after the page is trimmed.
  • Blowup An enlargement of a picture; or the process of enlarging a picture (to blow up).
  • Blur A photographic effect, either intentional or unintentional, that produces an picture with a loss of image sharpness.
  • BMP file A Microsoft Windows bitmap graphics file that has the extension .bmp.
  • Bounce light Light that is bounced off a reflective surface, such as any of the following: a white card, an aluminised reflector, a wall, or the ceiling.
  • Burn in To darken a small area of a picture; named after the process done in a darkroom, where all but the affected area is masked in order to give extra exposure to only the unmasked area.
  • Byte Short for binary term; a unit of storage capable of holding a single character; on almost all modern computers, a byte is equal to eight bits.
  • Card Memory chip that can be used to store images and data. Various forms currently exist, the most popular of which is Secure Digital (SD). Other formats include Secure Digital High Capacity (SCHC), CompactFlash, Sony Memory Stick and xD-Picture Card.
  • Catchlight A light placed so as to reflect tiny white dots in the eyes of a portrait subject.
  • CCD Short for charged coupled device; a mechanism that converts light into a proportional (analog) electrical current; the two main types of CCD are linear arrays, used in flatbed scanners and digital copiers, and area arrays, found in camcorders, digital cameras, and the like.
  • CGM Short for computer graphics metafile; this is an image file format designed to handle a wide range of image types.
  • Chroma A quality of colour, combining hue and saturation.
  • Chromatic aberration Also known as colour fringing, this problem is caused when the camera lens do not focus the different wavelengths of light onto the exact same focal plane. It usually happens around subjects with a wide contrast and around the edges of the image in wide-angle shots.
  • Close-up lens Lens that allows close photography; also called a macro lens.
  • CMYK Short for cyan, magenta, yellow, and black; colour model that defines the amount of colour by percentage.
  • Colour balance Means of compensating for too much of one colour in a photo by adding that colour’s opposite; for example, if a photo has too much blue, adding a larger percentage of yellow would help achieve a balance.
  • Colour temperature A means of measuring the relative redness or blueness of a light source; measured in degrees kelvin (K); higher numbers produce bluer light Typical incandescent bulbs are approximately 3,200 degrees K, while daylight is about 6,500 degrees K.
  • Colour wheel The circular relationship of all colours based on the frequencies of light at each colour.
  • Compression The reduction of data to reduce the size of a file; compression can be lossy (for example, JPEG images) or lossless (for instance, TIFF images); lossy images have a greatly reduced file size.
  • Continuous tone An image where brightness appears consistent and uninterrupted; each pixel in a continuous-tone image uses at least one byte for its red, green, and blue values. This allows 256 density levels per colour or more than 16 million colour mixtures.
  • Contrast A measure of the rate of change of brightness in an image; high contrast suggests content consisting of dark blacks and bright whites; medium contrast implies a good spread from black to white; and low contrast implies a small spread of values from black to white.
  • Crop The action of trimming away the unwanted parts of an image.
  • Cropping tool An applet found within photo-editing software that allows one to trim away unwanted parts of an image.
  • Cyan One of the three primary colours in colour prints (coupled with magenta and yellow).
  • Definition The clarity of detail in an image; dependent upon resolution (number of pixels) and contrast.
  • Depth of field Means of describing the area of a photograph that is in focus
  • Derived image An image that was created from another image.
  • Diaphragm This is another term for aperture.
  • Diffusion dithering A method of dithering that distributes pixels randomly rather than using a set pattern.
  • Digital Any system or device that stores information in a format suitable for computers to read; digital information is stored in bits, where each bit is represented as on/off or one/zero.
  • Digital camera A device that captures an image on a CCD (charged coupled device) so that the image file can be downloaded to and manipulated by a computer; does not use conventional film.
  • Digital image An image composed of pixels.
  • Digitisation The process of converting analog information into a digital format for use on a computer.
  • Disc Term used to describe optical storage media (laserdisc, compact disc).
  • Disk Term used to describe magnetic storage media (floppy disk, hard disk).
  • Dithering A method of simulating many colours or shades of grey by combining only a few; for instance, red and blue dots are dithered to make purple. Dithering allows a photo with millions of colours to be displayed on a 256-colour monitor and printed on a 4-colour printer
  • Dodging Also called holding back; in traditional darkroom work, the hand of the developer or a piece of cardboard would be used to block light passing from the enlarger to the print, thus lessening the exposure in only specific parts of the picture. Digitally, the effect is to lighten part of the image without affecting the rest.
  • DPI Short for dots per inch; a measurement based on the dot density of either a printer’s resolution or a video monitor image. For example, most laser printers have a resolution of 300 dpi, and most video monitors are set at about 72 dpi.
  • Dynamic range Refers to the gradations of light and dark that a digital camera can capture where details are neither washed out by light nor concealed by shadows.
  • EPS Short for Encapsulated PostScript; a type of graphics file that produces a high-quality image.
  • Export A software function that allows you to save a copy of information produced in one format into a file of another format.
  • Exposure The amount of light that reaches the film; the combination of f-stop and shutter speed, which controls the amount of light that passes through the lens to the film.
  • Exposure compensation In photography, exposure compensation allows you to intentionally under- or overexpose a shot to achieve a particular effect.
  • Exposure shift See exposure compensation.
  • File format A format for encoding visual information in a file; some common image file formats include TIFF, PICT, and EPS files.
  • Filter A tinted-glass or plastic lens that fits onto the camera lens to alter the visual field.
  • Flare The reflected light from lens elements that appears as a non-uniform haze or as bright spots on the film. This usually happens when a bright light directly enters the lens.
  • Flash card A memory card that works with the flash memory, allowing the camera to retain data after the system has been turned off.
  • Flash memory A memory chip that has the ability to retain image data even after the host system has been shut off; this feature insures that, even if the digital camera’s batteries die, the image data will remain stored in the camera’s memory.
  • Flatbed scanner This is an optical scanner in which the original image remains stationary while sensors scan the material from beneath the image.
  • Focal length The distance from the surface of the lens to the focal point or centre point at which light rays converge; the focal length determines the length of the lens.
  • Focal range This refers to the entire area that is in focus.
  • Focus To move the lens or film/image sensor in order to record a sharp image.
  • F-stop A means of measuring the width of the diaphragm opening, which determines how much light passes through the lens. Smaller numbers in an f-stop correspond to wider lens openings; as the f-stop reading increases in number, the lens opening decreases inversely.
  • Full-screen image A digital image that takes up the entire computer screen.
  • Gamut The range of colours that can be captured or represented by a camera or graphics device.
  • GIF Short for graphic image format; an image file format widely used on the Internet; provides high-quality image compression.
  • Grayscale A term used to describe an image that primarily contains shades of gray, as well as black and white.
  • Halftone An image that is reproduced through a series of dots to simulate shades of gray in a photograph; halftone has traditionally been used in the reproduction of images for newspapers and magazines.
  • High-key image A light, overexposed image, with few dark tones.
  • Highlight This is the lightest part of an image.
  • Hue The tint of a colour as measured by the wavelength of light. Hue is also represented by a position on the colour wheel.
  • Image capture The use of a device, such as a scanner or digital camera, to create a digital representation of an image. This digital representation can then be stored and manipulated on a computer.
  • Image editor A graphics program that provides a variety of special features for altering bit-mapped images for photographs and graphic images.
  • Image processing The manipulation of images that have been scanned or captured by a digital recording device.
  • Image stabilisation Image stabilisation, IS in short, helps to steady the image projected into the camera to compensate for hand shake. It differs from digital image stabilisation found in most digital video cameras as the later involves manipulation of image pixels to create a stable video image.
  • IR Short for infrared.
  • ISO See speed.

Digital photography glossary – J to Q

  • Jaggies This is a slang term referring to the jagged pixellisation effect that occurs in digital imaging.
  • JPEG Short for Joint Photographic Experts Group; this is a highly compressed image file, which takes an area measuring 8 by 8 pixels and compresses its information to the lowest common value. JPEG images tend to be lower in quality compared to other image formats, but their minimal size frees up room when dealing with limited storage space.
  • LCD Short for liquid crystal display; a small, flat, visual screen that employs liquid crystal technology in order to display images.
  • LED Short for light emitting diode; an electronic device that lights up when electricity passes through it. LEDs are usually red, and are used for camera viewfinder displays, since they can be seen in the dark.
  • Lens An optical device that focuses light rays. In cameras, the lens is the device on the front face (or in a tube extending from the front face) that gathers the incoming light and concentrates it so that it can be directed toward the film (in an optical camera) or the imaging device (in a digital camera).
  • Low-key image A dark underexposed image with few light tones.
  • LPI Short for lines per inch; refers to the frequency of horizontal and vertical lines on a halftone screen.
  • Luminence Refers to the black-and-white information, including brightness, sharpness, and contrast, encoded in a video signal or graphic image.
  • Macro The ability of a lens to focus at very close range.
  • Megapixel A measurement of 1,048,576 pixels (approximately 1 million pixels).
  • Memory Stick Sony Electronics-based storage media used predominantly in Sony’s cameras, computers, and MP3 players.
  • Moire pattern An unwanted effect that appears in digital scans of images.
  • Monochrome A term used to refer to a bi-level graphic; also refers to a single-channel grayscale image.
  • ND filter Short for neutral density filter; used to reduce the amount of light passing through a lens without altering the image’s colour or tonal rendition.
  • Neutral colour In RGB colour mode, equal amounts of red, green, and blue make a neutral colour.
  • Noise Refers to sound, signal, or data that was not originally intended to be included.
  • Normal lens A lens that accommodates an image of approximately the same angle of view and the same proportion as that of which the human eye is capable.
  • Opacity The amount of transparency when combining a fill colour, painted colour, floating selection, pattern, or layer with another layer or background.
  • Palette A computer graphics term describing the collection of colours or shades available to a graphics system or program.
  • Pan A camera technique in which the point of view is adjusted by moving the camera direction along the horizontal plane.
  • Phosphors Tiny red, green, and blue grains on the inside surface of a CRT monitor that are illuminated when an electron beam is directed toward them.
  • PhotoCD A popular storage method for digital images developed by Kodak.
  • PICT A Macintosh file format used for graphics.
  • Pixel Short for picture element; a pixel is a single point in a graphic image.
  • Pixelisation The graininess in an image that results when the pixels are too big, relative to the size of the image.
  • Polarisation This is the use of specific filters to control the direction light travels. Effects include the reduction of glare and reflections and the saturation of colours, especially in landscapes.
  • Polarising filter These are two pieces of polarising material that rotate on a common axis so that the polarising effect can be increased or decreased on the camera lens.
  • PPI Pixels per inch; the measurement of resolution for display or print elements.
  • Primary colours Three colours (red, yellow, and blue), which when combined at various proportions can produce every other colour.

Digital photography glossary – R to Z

  • Raster A pattern of scanning for input or output, which provides uniform coverage of a two-dimensional surface, such as a monitor screen, a scanner bed, or the CCD array in a digital camera.
  • Rasterisation The process of converting a graphic image to a bitmap.
  • Redeye A photographic phenomenon caused by light reflecting off the interior surface of the eye, which produces a red glare within the eye.
  • Reflectance Also called reflectivity, this is the fraction of the light incident on a surface that is reflected Reflectance varies according to the wavelength distribution of the light.
  • Relative aperture Also known as the f-stop, this is the diameter of the aperture of a camera divided by the focal length of the lens.
  • Resample To change the resolution of an image.
  • Resolution A measure of the proportion of the smallest individually accessible portion of a video image to the overall size of the image. The higher the resolution, the finer the detail that can be discerned.
  • RGB Short for red, green, blue; the colour model used for generating video on a display screen. It displays colours as varying intensities of red, green, and blue dots.
  • Sampling rate The number of samples obtained in a digitiSation process per unit of time or distance.
  • Saturation Also known as colour purity or the amount of colour density, the degree to which a colour is diluted by luminance, or white light.
  • Scale To enlarge or reduce an image by increasing or decreasing the number of scanned pixels.
  • Scanner An electronic input device that captures a digital image or objects into a computer.
  • SCSI Short for small computer system interface; a defined standard for the connection of mass storage and other input/output devices to a computer. A scanner or printer may employ a SCSI interface in order to communicate with a computer.
  • Shadow detail These are subtle features in the darker part of an image.
  • Sharpen A computer graphics process that enhances the contrast on the edges of light and dark shapes to make images appear more in focus.
  • Sharpness A reference to whether an image appears to be in focus.
  • Slide scanner The ratio of the usable signal to unusable noise in any signal. In imaging, this represents the quality of the scan.
  • Smoothing Also known as antialiasing, this is the electronic process of eliminating or reducing jaggies in an image.
  • Speed A rating that determines the light sensitivity of the film; ASA (American Standards Association) and ISO (International Standards Organization) provide a standard measure by which all photographic film speeds are determined. However, all digital cameras rate their CCD’s sensitivity as equal to that of a given ISO standard.
  • Stopping down In photography, this is the process used to decrease the size of aperture in a lens.
  • Subtractive primary colours Ink or other colourants, such as paint, that when combined together in equivalent amounts produce absolute black, or, when combined in different ratios, produce any colour other than black.
  • SVG Short for Scalable Vector Graphics – an XML-based vector image format for two- dimensional graphics with support for interactivity and animation.
  • SVGA Short for Super Video Graphics Array; defined by IBM; represents a computer graphics adapter capable of 800 by 600 resolution.
  • System palette A colour palette chosen by a computer system and applied to all digital images.
  • TGA Short for True Vision Targa File; a storage format for bitmapped video images.
  • Thumbnail A small representation of an image; used as an aid in indexing, previewing, or cataloging graphics images.
  • TIFF Short for Tagged Image File Format; a computer graphics file format developed by Aldus, Adobe, and Apple.
  • Truecolour A term used to describe an image that has a bit depth similar to the response of the human eye and which is considered to represent colour as seen through the human eye.
  • Value The relative lightness and darkness of a colour or tone.
  • Vector Graphics use geometrical primitives such as points, lines, curves, and shapes or polygons; (all based on mathematical expressions) to represent images in computer graphics. Vector graphics are based on vectors (also called paths or strokes), which lead through locations called control points or nodes. These points have a definite position on the x and y axes of the work plane, determining the direction of the path.
  • VGA Short for Video Graphics Array; defined by IBM; represents a computer-graphics adapter capable of 640 by 480 resolution. Also see SVGA.
  • Video digitiser Also called a frame-grabber, this is an image capture device that employs a video camera attached to a circuit board in a computer, which converts the video signal into a digital file.
  • Viewfinder An optical or electronic display used to frame an image in the camera. One looks through the viewfinder in order to see the image that will be captured by the camera.
  • Visible light The portion of the electromagnetic spectrum that the human eye can see, bordered on the “red” end by infrared, and on the “blue” end by ultraviolet.
  • VRAM Short for video random access memory; a special high-speed type of RAM that is used temporarily to store visual information being transferred to the display hardware in a computer.
  • White balance This is the balancing of colour components to create pure white when scanning a white object.
  • Wide-angle lens A lens that has an angle of view greater than that of a standard lens and that is considered of short focal length. This kind of lens is usually employed to include more of a subject within the confines of the image frame.
  • WYSIWYG Short for ‘what you see is what you get’, this term refers to the graphical interface that allows you to see onscreen what you will be able to print.
  • Zoom lens Lens with variable focal length within a certain range.

Windows Dev Centre, Overview of Vector Graphics  (accessed 22 April 2014)