13.2. Font Types.
There are 2 major sorts of fonts : Bitmapped fonts and
Outlined (Scalable) fonts. Outlined fonts are also known as
Vector fonts. Bitmapped fonts are fast falling out of fashion as
various outline technologies grow in popularity and support.
Bitmapped Fonts
- Bitmapped Fonts represent each character as a rectanglular
grid of pixels. The bitmap for each character indicates
precisely what pixels should be on and off. Printing a bitmapped
character is simply a matter of sending the right bits out to the
printer. There are a number of disadvantages to this approach.
The bitmap represents a particular instance of the character at a
particular size and resolution. It is very difficult to change
the size, shape, or resolution of a bitmapped character without
significant loss of quality in the image. On the other hand, it's
easy to do things like shading and filling with bitmapped
characters.
- Outlined Fonts (Vector/Scalable Fonts)
- Outlined fonts represent each character mathematically as a series
of lines, curves, and 'hints'. When a character from an
outlined font is to be printed it may be 'rasterized' into a
bitmap "on the fly". PostScript printers, for example, do this in
the print engine. If the "engine" in the output device cannot do
the rasterizing, some front end has to do it first. Many of the
disadvantages that are inherent in the bitmapped format are not
present in outlined fonts at all. Because an outline font is
represented mathematically it can be drawn at any reasonable
size. At small sizes, the font renderer is guided by the 'hints'
in the font; at very small sizes, particularly on low-resolution
output devices such as screens, automatically scaled fonts become
unreadable and hand-tuned bitmaps are a better choice(if they are
available). Additionally, because it rasterized 'on demand', the
font can be adjusted for different resolutions and 'aspect
ratios'.
There are many types of fonts around. Here are some of the type
of fonts that are commonly used.
- TrueType
- TrueType font is categorized as an outline font concept. It was first
developed by Apple Computer, Inc in 1991 and later introduced
by Microsoft. Currently it is used as the standard font format
on Microsoft platforms and its applications. The TrueType font
was originally designed to meet the 'What You See Is What You
Get' or WYSIWYG requirement. Therefore it gives the user great
visual help in preparing their documents or works in Windows
environment (and other platforms that utilized it). The suffix
for TrueType is ttf, for example, myfile.ttf .
- PostScript
- PostScript was invented by John Warnock and Charles Geschke from Adobe
Systems. It is a page description language (PDL) which is an
interpreted programming language to describe text, graphical
shapes and images. A PostScript font is categorized as outline
font, and therefore able to produce good quality text and images
on virtually any size. The suffix for PostScript font is usually
.ps . Some Laser Printers provide PostScript facility. If the
user doesn't have PostScript printer, there are utilities to
print it using non-PostScript printer via ghostscript or
ghostview program.
Most Unix tools expect to get character metric information from
AFM files. You may have difficulty using fonts collected off the
'Net if they did not include AFM files. - MetaFont
- MetaFont is a programming language for describing fonts. It was invented
by Donald Knuth. This programming language would produce raster
font when specified to display certain kind of font.
- Bitmap font
- Bitmap font contains a pattern of dots that display the character set it
represents. Usually it has the suffix .fnt
Fig. 13.2 : Other example of fonts.
