LaTeX and fonts

• Font formats
• How LaTeX uses fonts
• Using Postscript fonts in LaTeX
• LaTeX font attributes
• Associated LaTeX filetypes
• Associated LaTeX utilities
• LaTeX font names
• Things that can go wrong
• See Also
• Glossary

Introduction

In consequence, LaTeX's use of fonts isn't trivial for users or system managers, but usually isn't too hard either. These notes go way beyond what a standard LaTeX user needs, but might be useful when something doesn't work as expected.

Font formats

There are also several font formats. Systems (especially in the past) required separate screen fonts and printer fonts. Screen fonts are low-resolution, bitmapped images which don't scale well (so different point-sizes call for different images) and can take a lot of disc-space. Printer fonts are for the final hardcopy so they need to be high-resolution. They're often produced from a set of specifications which can produce different sizes and styles of characters according to requirements. Postscript (a page description language rich in curve-drawing and filling commands) can be used to define fonts. Postscript type 1 fonts were used in the 1980s and continue to be used. ATM (Adobe Type Manager) is a subset of the postscript interpreter that runs on the computer, not in the printer. It needs a single bitmap font plus a printer font. ATM scales Type 1 PostScript fonts for screen display and imaging for both PostScript and non-PostScript printers.

In the early 1990s TrueType emerged so scalable fonts could generate bitmaps on-demand as though each size had been designed by hand. On Windows such file have a .ttf suffix. Other formats exist too -

• Postscript Type 3 fonts - fonts that use extra postscript commands
• metafont - a format for describing and generating characters used in the [La]TeX world.
• OpenType is directly based on Unicode - an international standard for representing a broader character set using two-byte encoding for each letter. This allows the encoding of 64,000 characters instead of 256. OpenType puts either a PostScript or TrueType outline in a TrueType-style wrapper. Applications and most operating system functions outside of the font subsystem will no longer care which type of font is in this "wrapper".
• Apple Type Solution (ATS) is on new Macs. It provides support for various font formats including TrueType, PostScript Type 1, and OpenType.

More recently, many PostScript Level 2 printers (and all PostScript 3 printers) have TrueType rasterisation built in. However, with some Windows printer drivers the user must change the printer driver settings in software to take advantage of this feature (downloading TrueType as Type 42).

How LaTeX uses fonts

LaTeX's use of metafont fonts

• how the character might be affected by neighbouring ones ('f' followed by 'i' may form a ligature, for example)
• how elastic the space around the character is (LaTeX may want to squeeze a word to fit on a line)

• as a bitmap - PK files hold bitmaps at set resolutions. If the appropriate pk file isn't installed, it's generated from the metafont definition on-the-fly
• as a postscript character - leaving the postscript printer or viewer to render the fonts (though the postscript file can have embedded fonts).

Using Postscript fonts in LaTeX

• PostScript printers (and Adobe Type Manager) with 13 fonts have - Courier, Courier-Bold, Courier-BoldOblique, Courier-Oblique, Helvetica, Helvetica-Bold, Helvetica-BoldOblique, Helvetica-Oblique, Symbol, Times-Bold, Times-BoldItalic, Times-Italic, Times-Roman
• Postscript printers with 17 fonts have - Courier, Courier-Bold, Courier-BoldOblique, Courier-Oblique, Helvetica, Helvetica-Bold, Helvetica-BoldOblique, Helvetica-Narrow, Helvetica-Narrow-Bold, Helvetica-Narrow-BoldOblique, Helvetica-Narrow-Oblique, Helvetica-Oblique, Symbol, Times-Bold, Times-BoldItalic, Times-Italic, Times-Roman
• Postscript printers with 35 fonts have - All of the above, plus the following: ZapfChancery-MediumItalic, ZapfDingbats, AvantGarde-Book, AvantGarde-BookOblique, AvantGarde-Demi, AvantGarde-DemiOblique, Bookman-Demi, Bookman-DemiItalic, Bookman-Light, Bookman-LightItalic, NewCenturySchlbk-Bold, NewCenturySchlbk-BoldItalic, NewCenturySchlbk-Italic, NewCenturySchlbk-Roman, Palatino-Bold, Palatino-BoldItalic, Palatino-Italic, Palatino-Roman

LaTeX font attributes

• encoding - This specifies the order that characters appear in the font (e,g. whether the 65th character is 'A'). The most common value for TeX font encoding is OT1. The other predefined option is T1 (extended TeX). There's also US ASCII (7 bit), ISO Latin-1 (8 bit), Adobe Standard Encoding, etc.
• family - The name for a collection of fonts, usually grouped under a common name by the font foundry. For example, `Adobe Times' ptm and Knuth's `Computer Modern Roman' cmr are font families.
• series - How heavy or expanded a font is. For example, `medium weight', `narrow' and `bold extended' are all series.
• shape - The form of the letters within a font family. For example, `italic', `oblique' and `upright' are all font shapes.
• size - The design size of the font, for example `10pt'.

Associated LaTeX filetypes

• .tfm - tex font metric. [La]TeX needs the font metrics to properly layout the page. They're in $TEXMF/fonts/tfm/supplier/fontname/
• .afm - Adobe Font Metrics (files used by Type1 fonts). They're in $TEXMF/fonts/afm/supplier/fontname/
• .pfb - $TEXMF/fonts/type1/supplier/fontname/ - the type1 font directory
• .ttf - $TEXMF/fonts/truetype/supplier/fontname/ - TrueType fonts
• .pl - property list. This is a human readable version of a tex font metric file.
• .vpl - virtual property list. Human readable version of a virtual font file.
• .fd - font definition. Used to define a family of fonts. Contains information on how LaTeX font attributes are turned in TeX fonts. They're in $TEXMF/tex/latex/psnfss
• .vf - virtual font. These files contain encoding details, and act as interpreters. TeX treats them as fonts. It's a way of constructing a font from the characters of various other fonts (you may for example want a virtual font that uses all the characters of another font except that the dollar sign is replace by the euro symbol). They're in $TEXMF/fonts/vf/supplier/fontname/
• .pk - a device dependent bitmap font. These are usually constructed on an as-needed basis (renderings of Type1 and metafont fonts). On modern systems these generated .pk (and .tfm) files are stored so that anyone else can subsequently use them. On our system they're in /public/texfonts.
• .mf - metafont files. These are installed on our system in $TEXMF/fonts/source. A list of metafont fonts is online.
• .map - files mapping between the (manufacturer name, font name) and the TFM file. Note that one company's font called X may not have the same specification as another company's font of the same name.
• $TEXMF/dvips/config/psfonts.map - fontmap file for dvips. This file is similar in both function and format to ghostscript's Fontmap file. It maps TeX font codenames to postscript font specifications.

Associated LaTeX utilities

• afm2tfm - This will create a TFM files of raw fonts and vpl files of virtual fonts from an AFM file.
• ttf2tfm - TrueType to TFM
• ttf2afm - TrueType to AFM
• ttf2pt1 - TrueType to AFM and PFB
• vptovf - From a VPL file this creates vf and tfm files for virtual fonts.
• mf - processes a metafont file to produce TFM and PK files
• fontinst is a utility for font installation, originally written by Alan Jeffrey. Its primary purpose is to simplify the installation of PostScript or TrueType fonts for use with (La)TeX
• Use "xdvi -l filename" to list the fonts used by the file

LaTeX font names

• F is a one-letter abbreviation for the foundry (m = monotype, p = adobe, b = bitstream, f = free)
• N is a two letter abbreviation for the font name (for example, ag = "avant garde")
• W is the font weight (r = regular, b = bold, l = light d = demibold)
• V is an optional slope variant (i = italic , o = oblique)
• E is an abbreviation for the encoding (almost always 8a which is adobe standard encoding).
• N is an optional width variant (n = narrow)

Things that can go wrong

• The characters are all there, but spacing is strange - It may be that latex isn't using the TFM file appropriate for the font you're using.
• The main text is ok, but the maths isn't - the free postscript fonts lack many maths characters. The mathptm package puts the maths into the postscript Times font and symbol font where possible, otherwise it uses the metafont-generated characters. There are commercial alternatives, and free alternatives are under development.
• My postscript file looks bad onscreen - perhaps ghostscript's configuration file is wrong. ghostscript will try to use a default font if it doesn't know what to use.
• My postscript file looks ok on screen but fails to print - ghostscript has support for many more fonts than postscript printers have. Whereas ghostscript might substitute for a missing font, a printer is likely to abort the job.
• My postscript file is ok, but when I convert to PDF the fonts are slow and ugly - Use postscript fonts in the LaTeX file. See the TeX FAQ for details.

See Also

• As the need for big character sets (with more than 256 characters) increases, new formats and encodings are emerging. The LY1 encoding is an alternative to OT1. The Omega project adds wide-character support to TeX.
• The inputenc LaTeX package lets other encodings (e.g. ISO-Latin 1) be used.
• Frequently Asked Questions about fonts
• Using TrueType fonts with TeX (LaTeX) and pdfTeX (pdfLaTeX) by Damir Rakityansky.
• TrueType & PostScript Type 1: What's the Difference? (by Thomas W. Phinney)
• A Quick Primer on LaTeX/TeX fonts (Donovan Rebbechi)
• TeX font metric files for PostScript fonts (from the TeX FAQ)
• What are encodings? (from the TeX FAQ)
• Choice of scalable outline fonts (from the TeX FAQ - especially useful for math options)

Glossary

• anti-aliasing - a way to disguise the jagged lines that appear on low-resolution screens (using grey instead of black, etc).
• glyph - the final letter shapes that appear in the hardcopy
• hinting - The provision of additional information encoded in the font to help prevent problems caused by scaling, etc.
• italics - a sloping style of a font - not to be confusing with sloping or oblique text which is a simple mathematical transformation of characters
• kerning - adjustment of space between certain characters - sometimes so their bounding boxes overlap. For example, the 'o' of 'To' often goes under the crossbar of the 'T'.
• leading - (rhyming with 'wedding') space between lines of type
• ligatures - special characters joining certain characters (fi, ffl etc)
• monospace - a font where each character is the same width. The alternative is proportional spacing
• orphan - a paragraph's final word or line at the top of a column or page
• Postscript - a page description language, text drawing and graphics drawing being treated uniformly. Most printers support Postscript level 2 nowadays. Level 3 postscript hasn't been out long.
  • Type 1 font - a PostScript font specification which included hinting
  • Type 3 font - a font drawn using postscript commands, requiring a full PostScript interpreter. Most developers have stopped using this format except in a few special cases, where special type 3 characteristics (pattern fills inside outlines, for example) have been used. When non-postscript fonts are used in LaTeX and the resulting file converted to postscript, type 3 fonts are used, which look especially bad if the postscript file is subsequently converted to PDF.
• rasterisation - An outline font must be represented by the dots of the output device (screen pixels, dots of ink, etc). The process of converting the outline to a pattern of dots on the grid of the device is called "rasterisation". When there aren't enough dots making up the glyph (such as at small sizes or low resolutions), there can be inconsistencies in the representation of certain letter features due to different rounding based on how the outline happens to sit on the grid (e.g. when the widths of the letter stems vary when they shouldn't). Worse, key features of the glyphs can disappear at small sizes. Both PostScript Type 1 and TrueType fonts have a means of dealing with these inconsistencies, called "hinting".
• river - a vertical lining-up of word spaces on a page
• serif - a short stroke at the end of a character's main stroke. A sans serif font (helvetica for example) lacks these strokes
• typeface - a set of characters with the same basic shape for each letter
• Type 42 font - a TrueType font encapsulated in a PostScript wrapper so that it can be used like other PostScript fonts. Only recent versions of PostScript (starting with Adobe Postscript 2013) know how to deal with such fonts. Conversion of TrueType into Type 42 can be done by ttfps
• widow - a paragraph's final word alone on a line