Computer Graphics

The computer graphics glossary is an attempt to assemble some of the more common terms a writer is likely to come across when dealing with computer graphics. It's by no means an exhaustive list. If you don't find a term here, try the computer animation glossary or the desktop publishing glossary.

Click an index letter below to jump to terms:

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 #

additive colors: The additive colors are red, green, and blue. Adding these colors together creates white (all light reflects back to the eye).
Adobe: A family of programs used for electronic, web, and print publishing. Adobe produces great programs such as Photoshop, GoLive, and FrameMaker.
AI: Adobe Illustrator. Adobe Illustrator native file format.
aliasing: Visual artifacts produced in graphics images that use pixels for display. One example of aliasing is jagged edges on curved lines.
alpha: A fourth color component in the RGB color model representing opacity. Alpha values can range from completely transparent to completely opaque.
animated GIF: Solid-color motion graphic file format that doesn't include audio. It's best suited for small frame sizes, and ideal for use on the web.
anti-aliasing: Rendering techniques that reduce aliasing. It determines the color value of a pixel by averaging the color value of the pixels around it. This is usually based on some form of interpolation or oversampling.
ARB: Architecture Review Board. An independent consortium that governs OpenGL specifications, defines conformance tests and approves OpenGL enhancements. The board includes representatives from companies such as 3Dlabs, Compaq, Evans & Sutherland, Hewlett Packard, IBM, Intel, Intergraph, NVIDIA, Microsoft, and SGI.
Architecture Review Board: see ARB

bitmap: An grid of pixels assigned a color and X and Y locations. Bitmap images are resolution dependent, unlike vector graphics (which are resolution independent). Bitmap graphics are also known as raster images.
bleed: Printing that extends to the edge of a sheet or page of paper after it has been trimmed.
BMP: Bitmap. A standard Windows uncompressed image format. It supports RGB, indexed-color, grayscale, and Bitmap color modes. It doesn't support alpha channels.
butt: When two or more art or color elements meet edge to edge.

CCITT: A family of lossless compression techniques for black-and-white images. It's supported by PDF and Postscript file formats. (CCITT is an abbreviation for the French spelling of International Telegraph and Telekeyed Consultive Committee.)
CMYK: Cyan, Magenta, Yellow, black. The subtractive colors. Cyan (C), magenta (M), and yellow (Y) combine to absorb all color and produce a muddy brown. Black (K) ink is added to produce a true black. (K is used instead of B to avoid confusion with blue.) Combining these inks to reproduce color is called four-color process printing.
color index: A single value that represents a color by name, rather than by value.
color map: A table showing index-to-RGB mapping that's accessed by display hardware. Each color index is read from a color buffer, converted to an RGB triple by lookup in the color map then sent to the monitor.
color model: Models used to describe and reproduce color.
compression: Hardware and software techniques that reduce the storage space required by bitmap image data. There are two common techniques. The first, lossless, compresses image data without removing detail. The second, lossy, compresses images by removing detail.

DCS: Desktop Color Separations. A version of the standard EPS format developed by Quark. The DCS 1.0 format supports CMYK files without alpha channels and clipping paths. The DCS 2.0 format supports multi-channel and CMYK files with a single alpha channel, clipping paths and multiple spot channels.
dithering: Simulates unavailable colors using patterns that intersperse pixels from available colors. Dithered colors often look coarse and grainy.
dpi: dots per inch. The display resolution of devices such as monitors or printers.
DWG: AutoCAD Drawing. Standard file format for saving vector graphics created in AutoCAD.

EMF: Enhanced metaFile. Graphic file format available for Windows and WinNT. It saves both vector and pixel information
EPS: Encapsulated Postscript. Computer file containing Postscript commands with images.
extrusion: Extending a 2D object into 3D space by adding a z plane.

FLA: Flash project. Flash is used to create vector-based animation, interactive Web sites, and even games. Flash is a Macromedia product.

GIMP: GNU Image Manipulation Program. A freeware graphics application developed and maintained by Gimp.org as part of the open source movement. It's features are as robust as for-profit applications, like Photoshop.
GIF: Graphics Interchange Format. A common file format used to display indexed-color graphics and images for HTML documents. It can display interlaced lines of an image as it downloads. It can also store multiple bitmaps in one file, producing animated GIFs. GIF 89a supports transparency.
graphics engine: Software that generates interactive 2D and 3D graphics. Examples of graphics engines are Direct3D and OpenGL.
graphics library: A tool set for application programmers. It usually includes a defined set of primitives and function calls that enable the programmer to bypass many low-level programming tasks.
graphics pipeline: A sequence of operations that creates an image from user defined settings to final output. The pipeline determines how color information and geometric coordinates are processed in the hardware and software.
GZ: GIMP image file.

hexadecimal: 16 digits, 0-9 and A-F used to define color values in HTML. Hokum Home has a list of hexadecimal color values you can use when creating your own Web pages.
hue: A specific color, such as red or green.
HSB: hue, saturation, brightness. Based on the human perception of color, the HSB model describes three fundamental characteristics of color.; Hue is the color reflected from or transmitted through an object, such as red, green or blue. It's measured as a location on the color wheel and is expressed as a degree between 0 and 360 on that wheel.; Saturation, also called chroma, is the strength or purity of the color. Saturation represents the amount of gray in proportion to the hue and is measured as a percentage from 0% (gray) to 100% (fully saturated).; Brightness is the relative lightness or darkness of the color, usually measured as a percentage from 0% (black) to 100% (white).

ICO: Icon. Standard format for icon files.
IFF: Interchange File Format. The Amiga Interchange File Format is used for working with Video Toaster and transferring files to and from the Commodore Amiga system. It supports RGB, indexed-color, grayscale and Bitmap color modes. It does not support alpha channels.
interpolation: Literally: filling in the empty space between existing parts. Interpolation is used in graphics to describe the process of upscaling graphics.
illustration: A diagram, drawing, photograph, etc. which further explains or clarify the information contained in the surrounding body of text.

JPG (JPEG): Joint Photographic Experts Group. A commonly used graphics file format that uses lossy compression. It supports up to 24 bit color. Its small size makes it ideal for web graphics.

L*a*b* color model: Based on the model proposed by the Commission Internationale d'Eclairage (CIE) in 1931 as an international standard for color measurement. It's designed to be device independent; creating consistent color whatever the device (such as monitor, printer, computer, or scanner) used to create or output an image. L*a*b color consists of a luminance or lightness component (L) and two chromatic components: the a component (from green to red) and the b component (from blue to yellow).
In 1976, this model was refined and named CIE L*a*b.
line art: Art that contains no graded tones. Usually black on white (as in comic manga) or solid color on white. In either case there are no middle tones.
lossy: Image compression techniques that remove detail as they reduce file size.
lossless: Image compression techniques that don't remove detail as they reduce file size.
LZW: Lemple-Zif-Welch. A lossless compression technique supported by TIFF, PDF, GIF and Postscript file formats. It's most useful in compressing images that contain large areas of single color, such as screenshots or simple paint images.

Macromedia: A family of programs used for graphics and web development. They produce programs such as Dreamweaver and Flash. Macromedia purchased eHelp, makers of RoboHelp, in 2003.
moiré: A shimmering 'interference' pattern produced when two geometrically regular patterns are superimposed.
multimedia: An application or presentation that uses any combination of animation, audio, images, text, and video to deliver information to an audience.

OpenOffice.org (OOo): A suite of freeware productivity applications offered by OpenOffice.org that includes Writer (for word processing and document layout), Calc (for spreadsheets), Draw (for graphics and illustrations), and Impress (for presentations). The software is as robust as for-profit suites, such as Microsoft Office.

PCX: Commonly used by IBM PC-compatible computers. It supports RGB, indexed-color, grayscale and Bitmap color modes. It does not support alpha channels. PCX supports the RLE compression method.
PDF: Portable Document Format. Computer file format that contains vector and bitmap graphics, and can contain electronic document search/navigation features. The format allows for easy sharing of files between platforms.
PICT: Apple graphic file format. It can include bitmapped or vector images, and can use different compression schemes. It's available only for Apple.
pixel: picture element. The smallest element that can be independently assigned color.
PNG: Portable Network Graphics. Developed as a patent-free alternative to GIF, it's used for losslessly compressing and displaying images on the Internet. It supports 24-bit images and produces background transparency without jagged edges. It supports grayscale and RGB color modes with a single alpha channel, and Bitmap and indexed-color modes without alpha channels.
primitive: A point, a line, a polygon, a bitmap or an image.
PSD: Photoshop native file format. It contains layer and transparency information.

rasterize: The process of converting a projected point, line, polygon, or the pixels of a bitmap or image to fragments, each corresponding to a pixel in the framebuffer.
register: The correct alignment of colors during printing.
register mark: A symbol defining the correct alignment of overlay copy and color during printing.
resolution: For a CRT, the maximum number of displayable pixels in the horizontal and vertical directions. For a printer or plotter, the number of pixels per inch.
RGB (red, green, blue) color model: A color model. A large percentage of the visible spectrum can be represented by mixing red, green and blue (RGB) in various proportions and intensities. Where the colors overlap, they create cyan, magenta, and yellow. RGB colors are known as additive colors because they combine to form white. RGB colors are used for lighting, video and monitors. Hokum Home has a list of RGB color values that you can use.
RLE: Run Length Encoding. A lossless compression technique supported by Photoshop and TIFF file formats as well as some common Windows file formats.
rotation: A geometric transformation that causes points to be re-oriented about an axis.

saturation: The amount of color.
SDA: Draw document. Draw is the graphics application in the OpenOffice.org suite.
subtractive colors: Cyan (C), magenta (M), and yellow (Y). These colors combine to absorb all color and produce a muddy brown color. Black is added to produce pure black. Also known as CMYK.
SVG: Scalable Vector Graphics. Graphic file format developed for the web that uses vector graphics. The format produces higher resolution graphics with smaller file sizes.

TGA: Targa. Graphic file format that supports any bit depth, and includes features such as alpha channels, gamma settings and built in thumbnails.
TIF (TIFF): Tagged Image File Format. Graphics file format used to store images from scanners and video devices. It's the most common file format used in printing.
true color system: A 24-plane graphics subsystem which produces the complete range of 16.7 million available colors.

vector graphics: Images determined by mathematical functions utilizing besier curves. Vector graphics provide more flexibility for scaling than raster graphics.

WMF: Windows metaFile. Standard Windows graphics format supported by most Windows software.

3D graphics: A way of representing three dimensional data in two dimensional space.

Sources:

Print Publishing Guide
Dozens of web sites, too many to name really. I fully credit all of them for their insights and knowledge. If you see something you wrote, and want me to credit you, let me know!!

Writing Anthropology Tutorials

navigational divider

Reference Glossaries Bookstore Downloads

navigational divider

Site Info About Me Submit