Basic multimedia glossary

A special 8-bit grayscale channel that is used for saving a selection.

 

Animation is the process of playing back a timed sequence or series of graphic images or frames to give the appearance of continuous movement.

 

The blending of pixel colours on the perimeter of hard-edged shapes, like type, to smooth undesirable jagged edges.

 

(American Standard Code for Information Interchange) A standard editable format for encoding data.

 

The colour applied when the Eraser tool is used, the canvas size is enlarged, or a selection is moved on the Background of an image.

 

Bandwidth is the amount of information your connection to the Internet can carry. On average, typical telephone lines can carry 1K of information per second.

 

Adding a beveled effect to a graphic image gives the image a raised appearance by applying highlight colours and shadow colours to the inside and outside edges.

 

A curved line segment drawn using the Pen tool that can be reshaped by manipulating its anchor points or direction lines.

 

Machine language consisting of only 1's and 0's (on's and off's).

 

A binary digit is the smallest unit of information on a computer. Eight bits equal one byte.

 

The number of bits that are used to store a pixel's colour information for display. One byte is the basic unit of storage memory. 8 bits = 1 byte; 1024 bytes = 1 kilobyte (kB); 1024 kilobytes = 1 megabyte (MB); 1024 megabytes = 1 terabyte (TB).

 

The display of an image, on a computer screen via the geometric mapping of a single layer of pixels on a rectangular grid. In PhotoShop, Bitmap is also a one-channel mode consisting of only black and white pixels.

 

A PhotoShop tool that is used to darken an area of an image.

 

The full editable area of an image.

 

An image component that contains the pixel information for an individual colour. A grayscale image has one colour channel, an RGB image has three colour channels, and a CMYK image has four colour channels.

 

An area of memory used to temporarily store selection pixels. The Clipboard is accessed via the Cut, Copy, and Paste commands.

 

In PhotoShop, the automatic adjustment of colours to bring them into printable gamut.

 

(Cyan, Magenta, Yellow, and Black) The four-ink colours used in process printing. Cyan, magenta, and yellow are the three subtractive primaries. CMYK colours are simulated on a computer monitor using additive red, green, and blue light. To colour separate an image from PhotoShop, convert it to CMYK colour mode.

 

The adjustment of colour in an image to match original artwork or a photograph. colour correction is usually done in CMYK colour mode in preparation for process printing.

 

The production of a separate printing plate for each ink colour that will be used to print an image. Four plates are used in process colour separation, one each for Cyan, Magenta, Yellow, and Black. An addition plate is used for each spot colour.

 

The colour palette of up to 256 colours of an image in Indexed colour mode.

 

A method of packing data in order to save disk storage space or download time. JPEGs are generally compressed graphics files. Compression is a technique to make a file or a data stream smaller for faster transmission or to take up less storage space.

 

An image, such as a photograph, in which there are gradual transitions between shades or colours.

 

A tool used to trim away part of an image.

 

Short, fine lines that are placed around the edges of a page to designate where the paper is to be trimmed at a print shop.

 

(Desktop colour Separation) A file format for saving a CMYK image for colour separation, with the option for saving spot colour channels and alpha channels, and an optional low resolution file for previewing and laser printing.

 

The mixing of adjacent pixels to simulate additional colours when available colours are limited, such as on an 8-bit monitor or an 8-bit palette.

 

To bleach (lighten) an area of an image (as in the dodge and burn tool in photoshop),

 

(Dots per inch) A unit that is used to measure the resolution of a printer or image setter. Dpi is sometimes used to describe the input resolution of a scanner, but "ppi" is the more accurate term.

 

A grayscale image that is printed using two plates to enhance its tonal depth. A witone is printed using three plates. A quadtone is printed using four plates.

 

A continuous-tone printing process in which a solid printing medium is converted into a gas before it hits paper.

 

Embossing a graphic image adds dimension to it by making the image appear as if it were carved as a projection from a flat background.

 

(Encapsulated PostScript) An image file format that contains PostScript code and, in the case of PhotoShop, an optional PICT or TIFF image for screen display. EPS is a commonly used format for moving files from one application to another and also for colour separation.

 

Feathering the edge of a graphic image gradually dissipates the edge, making the edge look blurry.

 

The colour that is applied when a painting tool is used, type is created, or the stroke command is applied.

 

Stands for Graphics Interchange Format. GIF images are the most widely used graphic format on the web. GIF images display up to 256 colours.

 

A glow is the opposite of a shadow in that it creates a surrounding highlight of an image. A high radiance creates a soft, subtle glow and a low radiance creates a hard, bright glow, such as a neon glow.

 

A gradient is a gradual transition of colours. In PhotoShop, a graduated blend between the Foreground and Background colours that is produced using the Gradient tool. Many metallic images are gradients. Web images that use gradient fills as a special effect should be saved in a JPEG rather than a GIF format.

 

An image that contains black, white, and up to 256 shades of gray, but no colon In PhotoShop, Grayscale is a one-channel image mode.

 

A pattern of tiny dots that is used for printing an image to simulate continuous tones.

 

A numbering system which uses a base of 16. The first ten digits are 0-9 and the next six are A-F. Hexadecimal numbers are used to colour web pages. For example, the hexadecimal equivalent for the colour white is #FFFFFF.

 

A graph showing the number of pixels at each level of brightness in an image.

 

See Hue, Saturation, and Brightness.

 

The wavelength of light of a pure colour that gives a colour its name--such as red or blue--independent of its saturation or brightness. Hue is measured as a location on a colour wheel, expressed in degrees.

 

A high-resolution printer (usually between 1,270 and 4,000 dpi) that generates paper or film output from a computer file.

 

In PhotoShop, an image mode in which there is only one channel and a colour table that can contain up to 256 colours. All the colours in an Indexed colour image are displayed on its table--unlike an image in any other mode.

 

A process that occurs automatically when an image's dimensions or resolution are changed which results in re-colouring the pixels. Interpolation may cause an image to look blurry when it's printed. You can choose an interpolation method in PhotoShop from slower, but better, to faster but lower quality.

 

To reverse an image's light and dark values and/or colours.

 

(Joint Photographic Experts Group)
A compression method in PhotoShop that shrinks a file's storage size, but which can also cause image degradation as a result of data loss.

 

To adjust the horizontal spacing between a pair of characters.

 

The spacing between lines of type, measured from baseline to baseline.

 

The lightness (or brightness) of a colour, independent of its hue and saturation.

 

(Lines per inch/halftone frequency/screen frequency) The unit that is used to measure the frequency of rows of dots on a halftone screen.

 

The distribution of an image's light and dark values.

 

A method for specifying how colour information is to be interpreted. An image can be converted to a different image mode (RGB to Indexed colour, for example). A blending mode can be chosen for a tool or a layer to control how it affects underlying pixels.

 

A software method (also known as vector) that is used for describing and processing computer files. Object-oriented graphics and PostScript type are defined by mathematics and geometry. Bitmapped images, such as PhotoShop images, are defined by pixels on a rectangular grid.

 

The density of a colour or shade, ranging from transparent to opaque. In PhotoShop, you can choose an opacity for a tool or a layer.

 

A shape that is comprised of straight and/or curved segments that are joined by anchor points.

 

A Macintosh file format that is used to display and save images. Save a PhotoShop image as a PICT to open it in a video or animation program (but not for colour separation).

 

(Basic image elements) The individual dots that are used to display an image on a computer monitor.

 

(Pixels per inch) The unit that is used to measure the resolution of a bitmapped image.

 

Third-party software that is loaded into the PhotoShop Plug-ins folder which enables it to be accessed from a PhotoShop menu. Or, a plug-in module that comes with PhotoShop that is used to facilitate Import, Export, file format conversion, or other operations.

 

A unit of measure that is used to describe type size (measured from ascender to descender), leading (measured from baseline, to baseline) and line width.

 

Produces a special effect in an image by reducing the number of shades of gray or colours to a specified--usually Iow number.

 

The page description language created and licensed by Adobe Systems Inc. that is used to display and print fonts and images.

 

Inks that are used to print an image from four separate plates, one each for Cyan (C), Magenta (M), Yellow (Y), and Black (K). In combination, they produce an illusion of an even wider range of colours.

 

In PhotoShop, a screen display mode in which a translucent coloured mask covers selected or unselected areas of an image. Painting tools can be used to reshape a Quick Mask.

 

(Random Access Memory)
The system memory of a computer that is used for running an application and processing information, and for temporary storage.

 

The conversion of an object-oriented image into a bitmapped image. When an Adobe Illustrator graphic is placed or opened in PhotoShop, it is rasterized. All computer files are rasterized when they're printed.

 

Change an image's resolution while keeping its pixel count constant.

 

The fineness of detail of a digital image (measured in pixels per inch), a monitor (measured in pixels per inch--usually 72 ppi), a printer (measured in dots per inch), or a halftone screen (measured in lines per inch).

 

(RGB) Red, Green, and Blue transmitted light are used to project colour on a computer monitor. When pure Red, Green, and Blue light (known as the additive primaries) are combined, they produce white light. In PhotoShop, RGB colour is a three-colour-channel image mode.

 

The purity of a colour, independent of its hue and brightness. The more gray a colour contains, the lower its saturation is.

 

To digitize a slide, a photograph, or other artwork on a scanner using scanning software so that it can be displayed and edited on a computer.

 

(Also known as virtual memory) Hard drive storage space that is designated as work space for processing operations and for temporarily storing part of an image and a backup version of the image when there is insufficient RAM available for those functions.

 

Angles used for positioning halftone screens when producing film to minimize undesirable dot patterns.

 

(Screen ruling) The resolution (density of dots) on a halftone screen, measured in lines per inch.

 

An area of an image that is isolated so it can be modified while the rest of the image is protected. The moving marquee that denotes the boundary of a selection can be moved independently of its pixel content.

 

A custom mixed ink colour used in printing. A separate plate is used to print each spot colour. Pantone is a commonly used spot colour matching system. (See Process colour) Each spot channel holds data for an individual custom colour.

 

(Tagged Image File Format) A common file format that is used for saving a bitmapped image, such as a scan. A TIFF image can be colour separated and can contain colour management profiles.

 

The range of pixels within which a tool operates, such as the range of shades or colours the Magic Wand tool selects or the Paint Bucket tool fills.