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Tools for working with monochrome bitmap fonts

The monobit tools let you modify bitmap fonts and convert between several formats.

monobit's native format is yaff, a human-friendly, text-based visual format similar to the ones used by Roman Czyborra's hexdraw, Simon Tatham's mkwinfont and John Elliott's psftools. Details are given in the yaff font file format specification.

Monobit requires Python 3.9 or above. Install through pip install monobit. Some formats or features require additional packages; see Dependencies below for a list. These will be installed automatically if you use pip.

monobit can be used as a Python package or as a command-line tool.

Usage examples

Convert utility

Here are some examples of how to use the conversion utility.

monobit-convert --help

Display usage summary and command-line options

monobit-convert --help load --format=raw

Display usage summary and additional format-specific command-line options for conversion from raw binary.

monobit-convert fixedsys.fon

Recognise the source file format from "magic bytes" or suffix (here, a Windows font) and write fonts to standard output in yaff format.

monobit-convert roman.bdf to --format=unifont

Read font from BDF file and write to standard output as Unifont HEX.

monobit-convert fixed.psf to fixed.png

Read font in PSF format and write to disk as image in PNG format.

monobit-convert --format=c to --format=bdf

Read font from standard input as C-source coded binary and write to standard output as BDF.

The converter transparently reads and writes gz, bz2, or xz-compressed font files and can read and write zip and tar archives. Some font formats contain multiple fonts whereas others can contain only one; the converter will write multiple files to a directory or archive if needed.

It is also possible to apply various transformations on the font before saving it. Check monobit-convert --help for usage.

Banner utility

The banner utility renders text to standard output in a given font. This is similar to the ancient banner commands included in System-V and BSD Unixes.

For example, the banner at the top of this README was made with

me@bandit:~$ monobit-banner '| monobit. |' --font=VGASYS.FON

monobit-banner has a number of rendering options - you can choose fonts, change the "ink" and "paper" characters, set a margin, scale text, and rotate by quarter turns. Check monobit-banner --help for usage.

Proportional-spacing formats

Format	Short Name	Typical Extension	Read	Write
Xerox Alto CONVERT	alto	.al	✓
Amiga Font Contents	amiga-fc	.font	✓
Amiga font	amiga		✓
X11/Adobe BDF	bdf	.bdf	✓	✓
Xerox Alto BITBLT	bitblt	.strike .ks	✓
AngelCode BMFont [P]	bmfont	.fnt .xml .json + images	✓	✓
Consoleet / vfontas	consoleet	.txt	✓
Daisy-Dot	daisy	.nlq .nl2 .nl3 .nl4	✓
DosStart!	dosstart	.dsf	✓
EDWIN bitmap font	edwin	.fnt	✓	✓
Figlet font	figlet	.flf	✓	✓
FZX font	fzx	.fzx	✓	✓
OS/2 GPI resource	gpi	.fnt	✓
C64 GEOS ConVerT	geos	.cvt	✓
Atari GDOS / GEM	gdos	.fnt .gft .vga	✓	✓
hexdraw	hexdraw	.draw	✓	✓
HP PCL soft font	hppcl	.sft .sfp .sfl	✓	✓
Apple IIgs font	iigs	.fon	✓	✓
Bitmap image [P]	image	.png .gif .bmp	✓	✓
Set of Bitmap images [P]	imageset	.png .gif .bmp	✓	✓
LISA font library	lisa	.bin	✓
MacOS font	mac	.dfont .suit	✓	✓
mkwinfont text format	mkwinfont	.fd	✓
Windows or OS/2 font	mzfon	.fon .exe .dll	✓	✓ (16-bit Windows)
Bare NFNT resource	nfnt	.f	✓	✓
Palm OS font (v1/NFNT)	palm	.pdb	✓
X11 Portable Compiled Format	pcf	.pcf	✓	✓
PCPaint, GRASP, ChiWriter	pcpaint	.set .fnt .sft .pft .eft ...	✓
PILfont [P]	pilfont	.pil + .pbm	✓	✓
TeX PKFONT	pkfont	.pk	✓
Adobe Prebuilt Format	prebuilt	.bepf .lepf	✓
Xerox Alto PrePress	prepress	.ac	✓
The Print Shop	printshop	.pnf	✓
Signum! 2	signum	.e24 .p9 .p24 .l30	✓
SFont	sfont		✓	✓
SFNT embedded bitmap	sfnt	.otb .ttf .otf [F] [**]	✓	✓ (OTB)
SFNT collection	ttcf	.otc .ttc [F] [**]	✓	✓ (OTB)
vfont	vfont		✓	✓
Bare GEOS resource	vlir		✓
Windows FNT resource	win	.fnt	✓	✓
monobit yaff	yaff	.yaff	✓	✓

[P] requires PIL
[F] requires fontTools

Character-cell formats

Format	Short Name	Typical Extension	Read	Write
64C	64c	.64c	✓	✓
+3DOS	plus3dos		✓	✓
BBC soft font	bbc		✓	✓
Codepage Information	cpi	.cpi	✓	✓
Dashen	dashen	.pft	✓
DEC DRCS soft font	dec		✓	✓
Dr. Halo / Dr. Genius	drhalo	.fon	✓
FONTX2	fontx	.fnt	✓	✓
FONTEDIT	fontedit	.com	✓
Fontraption	frapt	.com	✓
Fontraption TSR	frapt-tsr	.com	✓
Hanzi Bitmap Font	hbf	.hbf + raw binary	✓	✓
GNU Unifont	unifont	.hex	✓	✓
Extended Hex	pcbasic	.hex	✓	✓
Bare codepage	kbd	.cp	✓	✓
LETAFONT loader	letafont	.com	✓
REXXCOM Font Mania	mania	.com	✓
Optiks PCR Font	pcr	.pcr	✓
PC Screen Font	psf	.psf .psfu	✓	✓ (version 2)
PSF2AMS PSFCOM	psfcom	.com	✓
PSF2TXT	psf2txt	.txt	✓
Raw binary	raw	.fnt .rom [*]	✓	✓
UDG loader	udg	.com	✓
Hercules Write On!	writeon	.wof	✓	✓
Wyse-60 soft font	wyse		✓	✓
XBIN font section	xbin	.xb	✓	✓

Charts (write only)

Format	Short Name
Text or blocks	chart
Image [P]	chart
PDF chart [R]	pdf

[P] requires PIL
[R] requires reportlab

Stroke (vector) formats

Stroke font support is experimental. Stroke fonts are scalable fonts defined as line segments. They are fundamentally different from modern fonts in that they define single strokes whereas modern fonts define outlines to be filled with ink. Additionally, the fonts currently supported consist of straight line segments only.

Format	Short Name	Typical Extension	Read	Write
monobit yaff	yaff	.yaff	✓	✓
SVG Fonts	svg	.svg	✓	✓
Windows resource	win	.fnt	✓	✓
Windows font	fon	.fon	✓	✓ (NE)
Borland Graphics Interface	borland	.chr	✓	✓
Hershey fonts (Jim Hurt)	hurt	.jhf	✓
DOSStart	dosstart	.dsf	✓
GIMMS	gimms	.bin	✓

Wrapper formats

monobit will recurse and extract font files from a number of common container, archive, compression and encoding formats:

Format	Name	Typical Extension	Read	Write
PKZip/WinZip	zip	.zip	✓	✓
GNU tar	tar	.tar .tgz	✓	✓
RAR [A]	rar	.rar	✓
7-Zip [A]	7zip	.7z	✓	✓
MS Cabinet [A]	cabinet	.cab	✓
LHarc/LHA/LZH [A]	lharc	.lha .lzh	✓
ACE [C]	ace	.ace	✓
ISO 9660 [A]	iso9660	.iso	✓	✓
WARC [A]	warc	.warc	✓	✓
CPIO [A]	cpio	.cpio	✓	✓
PAX [A]	pax	.pax	✓	✓
XAR [A]	xar	.xar	✓	✓
AR [A]	ar	.ar	✓	✓
GZip	gzip	.gz	✓	✓
BZip2	bzip2	.bz2	✓	✓
XZ/LZMA	lzma	.xz .lzma	✓	✓
Compress [Z]	compress	.Z	✓	✓
AppleSingle	apple1	.as	✓
AppleDouble	apple2	.adf .rsrc	✓
MacBinary	macbin	.bin	✓
BinHex 4.0	binhex	.hqx	✓
BinSCII	binscii	.bsc .bsq	✓
Intel Hex	intel	.ihex .ihx	✓	✓
Base64	base64		✓	✓
Quoted-printable	quopri		✓	✓
UUEncode	uuencode		✓	✓
yEncode [Y]	yenc		✓	✓
MIME multipart email	email	.eml .msg	✓	✓
C or C++ coded binary	c	.c .cpp .cc .h	✓	✓
JSON coded binary	json	.json	✓	✓
Python coded binary	python	.py	✓	✓
Pascal coded binary	pascal	.pas	✓	✓
BASIC coded binary	basic	.bas	✓	✓

[A] requires libarchive
[C] requires acefile
[Y] requires python3-yenc
[Z] requires ncompress

Note that many of these currently require reading the full archive into memory, which may not be practicable with e.g ISO9660 or WARC files which can hold whole filesystems.

[*] Identifying raw binary files

This is the most common format used on old platforms, often with the unhelpful suffix .fnt. As there is no metadata, it's up to you to specify the character-cell size. The most common, and default, size is 8x8 (CGA and many 8-bit platforms), followed by 8x16 (VGA) and 8x14 (EGA).

• 8x8 raw files are also known as .f08, .ch8, .88, .chr, .udg, and many others.
• 8x14 raw files are also known as .f14 or .814.
• 8x16 raw files are also known as .f16, Warp 9 .fnt or Degas Elite .fnt
• Genecar .car files are 16x16 raw files.
• Harlekin III .fnt files are raw binaries with a 4096x8 pixel bitmap strike hosting 512 8x8 glyphs side by side. Extract with -strike-width=512.

It is also useful to check the file size. Raw files commonly hold 96 (ASCII excluding controls), 128 (ASCII), 256, or multiples thereof. Common file sizes therefore are:

	8x8	8x14	8x16
96	768	1344	1536
128	1024	1792	2048
256	2048	3584	4096
512	4096	7168	8192

If your unidentified font file has one of these sizes, chances are it is a raw binary file.

[**] TrueType / OpenType embedded bitmaps

monobit can extract bitmaps embedded in TrueType and OpenType font files. It should be kept in mind that these are primarily intended as scalable formats, and only exceptionally embed bitmaps to improve rendering on low-resolution displays.

The vast majority of .ttf, .otf, .dfont etc. files do not contain bitmaps at all. This is true even for fonts with a pixelised look. To convert these you first need to rasterise them, which monobit does not do. Some of the other font tools linked below do have rasterising features.

monobit can experimentally output OpenType Bitmap (.otb) files, a bitmap-only file format supported by Linux desktops.

Font format features

Here is a comparison of what you can and cannot store in selected formats supported by monobit.

Format	Unicode	Unicode sequences	Encoding	MBCS	Multiple fonts	Cell size	Proportional	Kerning	Colour/antialiasing	Glyph representation
yaff	✓	✓	✓	✓	✓	any	✓	✓		visual text
sfnt	✓	✓	✓	✓	✓	any	✓	✓	✓	binary
bmfont	✓		✓	✓		any	✓	✓	✓	image
mac			✓			any	✓	✓	✓	binary
bdf	✓		✓	✓		any	✓			hex
win			✓		✓	any	✓			binary
hexdraw	✓					any	✓			visual text
amiga					✓	any	✓		✓	binary
gdos						any	✓			binary
fzx						any	✓			binary
figlet	✓					any	✓		✓	visual text
vfont						any	✓			binary
pcbasic	✓	✓				8xN	multi-cell			hex
unifont	✓					8x16	multi-cell			hex
hbf			✓	✓		any				binary
psf (v2)	✓	✓				any				binary
psf (v1)	✓					8xN				binary
fontx				✓		any				binary
cpi			✓		✓	8xN				binary
dec						>4xN				binary
bbc						8x8				binary

Dependencies

Some formats require

• PIL (Pillow)
• reportlab
• fontTools
• libarchive
• python3-yenc
• ncompress
• acefile

The renderer additionally employs

• uniseg
• python-bidi
• arabic-reshaper

All can be installed through Pip:

pip install Pillow reportlab fonttools uniseg python-bidi arabic-reshaper libarchive-c python3-yenc ncompress acefile

Without these packages, some functionality may not be available.

Copyright and licences

monobit and the yaff specification are copyright 2019--2024 Rob Hagemans and released under the MIT licence.

monobit contains code from:

• mkwinfont copyright 2001 Simon Tatham. All rights reserved.
• dewinfont copyright 2001,2017 Simon Tatham. All rights reserved.
• OS/2 GPI Font Tools (C) 2012 Alexander Taylor
• FONDU copyright (C) 2000,2001,2002,2003 by George Williams

Please refer to the notices in the windows and os2 subpackages and mac/fond.py module for licences and more information.

The font files in tests/fonts are subject to their own licences, some of which are more restrictive. These are files used for testing and development and are not included in the packaged distribution. See tests/fonts/README.md and notices included with individual files.

Acknowledgements

monobit would not exist without those documenting, reverse-engineering, implementing and preserving font formats and files:

• The Internet Archive
• Archive Team
• Jason Scott's textfiles.com
• John Elliott's homepage
• Simon Tatham's fonts page
• Aivosto's character set documentation
• Rebecca Bettencourt's character set documentation
• Xiphoseer's Signum Document Toolbox
• George Williams et al.'s FontForge documentation
• FreeType Glyph Conventions
• ... and many others

Other software

Other bitmap font tools you could use in conjunction with (or instead of) monobit include:

• FontForge
• Rebecca Bettencourt's Bits'n'Picas
• John Elliott's PSFTools
• Mark Leisher's gbdfed
• RECOIL
• John Zaitseff's console font utilities
• George Williams's Fondu
• VileR's Fontraption