Vector graphics are generated by Computer Aided Drafting (CAD) applications and illustration programs based on Postscript such as Adobe Illustrator and Macromedia FreeHand. images are drawn on screen or printed based on vectors, the results of mathematical descriptions that determine the position, length, and direction in which lines are drawn. The image, because it is based on formula, can be scaled almost infinitely without distortion and is said to be “device independent.” This means that the image is translated faithfully from relative coordinates to the absolute coordinates of the device on which it will be viewed, such as a 72 dpi monitor. Then, as device resolution improves such as when the image is printed to a 300 dpi printer or a 1200 dpi typesetter, so does the quality of the image.

Bitmap graphics are created by paint programs such as Microsoft Paint or MetaCreations Painter. These images are “device dependent.” They are a fixed resolution based on screen pixels. A “bit” is the smallest unit of information handled by computers and is represented by either 1 or 0 in the binary numbering system. Computer screens draw images using pixels (small dots or rectangles). A black and white bitmapped image has pixels turned on or off which represents one bit per pixel. A color image is made up multiple bits per pixel which define color depth and other information. Therefore, bitmap graphics are made up dots or rectangles that are mapped to screen pixels.

Since bitmapped graphics are made up of dots, as opposed to shapes, they become distorted when scaled on screen or when printed at a higher resolution than the screen on which they were created. The image becomes broken or “stair-stepped” as the dots composing the original image start to become obvious to the eye.

Postscript, as pointed out above, is a vector graphics format that is referred to as a “page description language” which was developed by Adobe Systems in the mid-1980s. Postscript uses English-like commands that describe elements in the image such as line widths, colors and gradations, the use of scalable outline fonts, and where to place these elements on a printed page. This page description language was the first to give the computer user such a high level of control over images and text that it was said to be WYSIWYG (What You See Is What You Get). You could be confident when working with a Postscript application that the output from a Postscript compatible printer would be a faithful reproduction of the screen image.

Postscript allowed type designers to design digital typefaces with a degree of precision that was unheard of until this point. Kerning information, ligatures, true italics, and a full compliment of punctuation and symbols could be included in the Postscript definitions of fonts. These fonts are also called “Type 1” fonts distinguishing them from TrueType. The image of the font, as it is displayed on screen, is referred to as a screen font and are bitmapped and scalable only with the help of Adobe Type Manager (ATM). The part of the font which contains the postscript definition is called an outline font and it is this information that gets sent from the desktop computer to the laser printer which will print the image at the resolution of that specific printer.

TrueType, another vector format font technology, was developed by Apple and Microsoft. It is also scalable, much like Postscript, but uses mathematical formulas that are more similar to Computer Aided Drafting (CAD), as opposed to a proprietary page description language. With TrueType, no screen font is required, and no special printer is needed to print TrueType fonts.

Both of these font technologies are viable and can be used together or separately to produce similar results, but many print designers, as well as type designers, prefer the Postscript Type 1 fonts over TrueType. The precision that is built into the Postscript language gives the designer more control over character and word spacing, than does TrueType. TrueType fonts are plentiful and inexpensive, or even free, but be aware that, as with anything else, you get what you pay for.