Graphics
The creation, editing, and printing of pictures. Computer graphics has two main methods: vector graphics (stored as a list of vectors) and raster or bitmap graphics (stored as a collection of dots or pixels).

Halftone, or Halftone Screen
Grey tones of a photograph or piece of art accomplished with a dot pattern.

High Resolution
The high number of dots per square inch required to produce a high-quality image in printing or on a computer display screen. The higher the resolution, the finer the image quality. Good laser or inkjet printers and scanners provide a resolution of 600 dots per inch

Image Editor
A program that can be used to make changes in computer graphics. The program can be used to crop enhance paint and filter scanned images. Adobe Photoshop is an example of an image editing tool. Some page layout programs such as Quark and Pagemaker allow image editing after the image has been imported.

Image Format
A format in which an image can be stored and used. Some formats, such as TIFF and PICT, can be imported into many different programs and transferred between different platforms. GIF and JPEG are formats used for images on HTML pages. There are image conversion tools in some programs (for example, Photoshop), which make it possible to change from one format to another.

Impression
A single image transferred by a printing device to one side of a sheet of paper.

JPEG
Joint Photographic Experts Group. A format for storing high-quality color and grayscale photographs in bitmap form; also the group that developed the format. JPEG provides lossy compression by segmenting the picture into small blocks which are divided to get the desired ratio; the process is reversed to decompress the image. JPEG uses the JPEG File Interchange Format, or JFIF.

Kerning
Reducing the spacing between certain pairs of letters in a proportional-pitch type to improve the appearance of the line of type. For example, A and V look better next to each other if they are moved closer together than, for example, A and B.

line frequency
The number of lines counted vertically used by a printer to create an image.

lpi
Lines Per Inch. A measurement of the resolution of a halftone screen, or of the number of lines a printer prints on a page in each vertical inch.

PostScript
A page description language from Adobe Systems, Inc. PostScript translates the text and graphic images that appear on the computer screen into instructions for the printer. PostScript must be used with a printer that can interpret it.

Raster Graphics
Bitmapped graphics; computer graphics in which the image is made up of tiny dots, called pixels.

Simplex Printing
Printing on one side of the page. Use one side of paper.

TIFF
Tagged Image File Format. A bitmap graphics file format that was developed by Aldus and Microsoft for storing scanned images. It can be used with black and white, gray scale, 8-bit color, and 24-bit color images, and transfers well between different platforms.

Vector Graphics
Graphic images represented in the computer as instructions to draw lines or objects, rather than as bitmaps (raster graphics).

WYSIWYG
What You See Is What You Get. Refers to the ability of a computer to present an image of a page layout or graphic on its screen that shows how the actual page will look like when it comes out of the printer.

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