A Brief History of Digital Type
With the advent of desktop publishing, type design and manufacturing entered a new era. The “analog” letterforms of metal and photo type were converted to a variety of digital formats. The first generation of technology resulted in “bitmap” fonts – comparable to superimposing a sheet of graph paper over a drawn letter and coloring in the boxes (pixels) that fell within the outline of that letter. Bitmapped fonts had the advantage that they could be carefully edited for quality and readability. They also had, however, the disadvantage of requiring a separate font for each size and resolution, thereby taking up a relatively large amount of memory.
The next, and current, generation of digital font technology provides for “scalable” outline fonts. They are smaller in memory size and faster to process. Analog drawings of letters are plotted with a mouse or stylus to create an outline representation (made up of curves and straight lines). These digitized outlines are made into a font that is installed in a computer operating system.
An application program (such as Microsoft Word or Quark Xpress) will scale the outline font to the requested size (like 12 point) and resolution (a 72 dot per inch [dpi] screen or 600 dpi laser printer, for instance). The outline is then “scan converted” or “rasterized”, which turns on pixels that lie within the area of the scaled outline. The resulting image is then sent to a screen or printer.
The resulting bitmaps at small sizes and resolutions (particularly video display screens) may be of poor quality, due to there being fewer pixels with which to render the fine detail of a letterform. Font technologies in use today (primarily PostScript, True Type, Microtype) have strategies for improving the quality for greater readability. Variously called “hints”, “instructions” or “intelligence”, the intent is to identify key features of the members of the font and ensure they behave consistently when displayed. For example, the widths of the 3 stems of a lower case “m” need to be the same number of pixels to be properly readable at small sizes. Hints improve the consistency of letterform shapes and their alignment when rasterized.
Additionally, the True Type technology allows for a greater degree of control over which pixels are turned on or left off. Sometimes called “delta” hinting or “ESQ” hinting (for Enhanced Screen Quality), specific areas of an outline letter can be addressed at specific sizes and resolutions. An example is the corner of a round shape, which may look too “boxy”. The corner pixel can be turned off, resulting in a smoother, rounder, shape. The spacing of a font can be adjusted as well, adding or subtracting pixels of white space between letters. For more about ESQ hinting, visit the Monotype Imaging site.
The cumulative effect of hinting will be improved color consistency and readability when the font is used on an output device.
- Editor’s Note:Ilene Strizver, founder of The Type Studio, is a typographic consultant, designer and writer specializing in all aspects of typographic communication. She conducts Gourmet Typography workshops internationally. Read more about typography in her latest literary effort, Type Rules! The designer's guide to professional typography, 3rd edition, published by Wiley & Sons, Inc. This article was commissioned and approved by Monotype Imaging Inc.