Editing Computer font (section)

==== Scaling ====
Bitmap fonts look best at their native [[pixel]] size. Some systems using bitmap fonts can create some font variants algorithmically. For example, the original [[Apple Macintosh]] computer could produce bold by widening vertical strokes and oblique by [[Shear mapping|shearing]] the image. At non-native sizes, many text rendering systems perform [[Nearest-neighbor interpolation|nearest-neighbor resampling]], introducing rough jagged edges. More advanced systems perform [[Spatial anti-aliasing|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 [[emulator]]s, 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.

The difference between bitmap fonts and outline fonts is similar to the difference between bitmap and vector image file formats.  Bitmap fonts are like image formats such as ''[[Windows bitmap|Windows Bitmap]]'' (.bmp), ''[[Portable Network Graphics]]'' (.png) and ''[[TIF|Tagged Image Format]]'' (.tif or .tiff), which store the image data as a grid of pixels, in some cases with compression. Outline or stroke image formats such as ''[[Windows Metafile]]'' format (.wmf) and ''[[Scalable Vector Graphics]]'' format (.svg), store instructions in the form of lines and curves of how to draw the image rather than storing the image itself.

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.