Bitmap font

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An assortment of bitmap fonts from the first version of the Macintosh operating system.

A bitmap font is one that stores each glyph as an array of pixels (that is, a bitmap). It is less commonly known as a raster font.

1 Drawing
2 Scaling
3 Bitmap font formats
4 Uses outside computing

[edit] Drawing

To draw a string using a bitmap font means to successively output bitmaps of each one character that the string comprises of, performing per-character indentation. As well as true type fonts, bitmap fonts can be monospaced (i.e.. every character is plotted a constant distant next to the previous one, while drawing) or proportional (each character has its own width). However, it depends on the font-handling application how each font will be displayed.

Unscaled bitmap fonts have the advantage of being considerably faster and simpler to render than outline fonts, since they can be copied to the output device with little or no preprocessing.

[edit] Scaling

Bitmap fonts look best at their native pixel size. At non-native sizes, many text rendering systems perform nearest-neighbor resampling, introducing ugly jagged edges. More advanced systems perform anti-aliasing on bitmap fonts whose size does not match the size that the application requests. This technique works well for making the font smaller but not as well for increasing the size, as it tends to blur the edges. Some graphics systems that use bitmap fonts, especially those of emulators, apply curve-sensitive nonlinear resampling algorithms such as 2xSaI or hq3x on fonts and other bitmaps, which avoids blurring the font while introducing little objectionable distortion at moderate increases in size.

A "trace" program can follow the outline of a high-resolution bitmap font and create an initial outline that a font designer uses to create an outline font useful in systems such as PostScript or TrueType. Outline fonts scale easily without jagged edges or blurriness.