N.B. An asterisk before a word means it has its own entry in the glossary.
A program that converts an *outline graphic to a raster, or *bitmap. The *scan-converter is the most important part of the rasterizer.
All scalable font systems need a rasterizer, to convert their *glyph outlines into bitmaps suitable for direct copying to the screen. The TrueType rasterizer, in common with most others, has a *hinting system. Atypically, this takes the form of a programming language.
See the TrueType Rasterizer page.
- reference point
In the *graphics state of TrueType *hinting are 3 reference points (rp0, rp1, rp2). These are simply numbers used to index particular *glyph points or *Twilight Zone points. Many TrueType *instructions use a combination of a *zone pointer and a reference point to identify a point to be moved or measured. Reference points are set explicitly with the instructions SRP0, SRP1 and SRP2, but in real hinting code it can be more efficient to let other instructions (e.g. MIRP) set them.
The fineness of an output device, nearly always measured in dpi (dots per inch). Resolutions quoted for screens are usually notional, in that the value differs from the true number of pixels per inch. Many screens can be set to various different settings (e.g. 800 by 600, 1024 by 768, 1600 by 1200), while the system treats them all as having the same dpi. Some standard resolutions:
- The Macintosh screen is taken to be 72 dpi;
- The PC's VGA screen resolution is notionally 96 dpi;
- Fax resolution is 100 or 200 dpi;
- Most early laser printers were 300 dpi;
- Good current laser printers are usually 600 dpi, occasionally 1200 dpi;
- Imagesetter resolution for high quality printing is 2400 or 2540 dpi (100 dots/mm).
The exciting, scriptable "typehacktool", based on *Fontographer 3.5 and *FOG-Q, from the creative minds of Petr van Blokland, Erik van Blokland and Just van Rossum. Find out more on the official RoboFog website.
- RSB (right side-bearing)
The offset from a *glyph's maximum extent in the x direction to its *advance width position - usually a positive value. RSB values are not stored explicitly in TrueType fonts (or most other font formats); rather, they may be calculated from the stored values for *LSB, advance width and the glyph's bounding box.
TrueType Typography |