Pleasures of Design

Quality of typefaces
The way in which typefaces are made has changed very rapidly. For 500 years type was cast in metal; today it is produced by digital output from a computer.

The letter form is broken up into a raster or grid of fine dots called “pixels”. The quality of the drawing of the letterform will depend very much on the fineness of that grid.

A fairly coarse grid – 300 dpi (dots per inch) – is referred to as low resolution. In this case the original drawing will have been simplified to suit the limited number of pixels available.

In a high resolution output device, the grid is finer – up to 2540 dpi and more. The amount of detail that can be achieved depends on the size of type. The number of dots to the inch is the same for both large and small sizes of the same typeface, so the larger the size the more dots are available to draw the shape of the letter. This is particularly critical at low resolutions.

From the point of view of layout, much of this will be of academic interest but it is important to understand the difference between high and low resolution so that you can decide when to specify one or the other.

Choice may be limited by the equipment available. Most office laserprinters for instance, generate type at low resolution. Otherwise it is usually a compromise between high quality and economy. For example it would probably be uneconomic to produce at high resolution an internal document of which you needed only 50 copies. A publicity brochure to be widely distributed would not look good enough with type set at low resolution and should be output on a high resolution imagesetter.