# BDF Font (/main-modules/fonts/bdf_fonts)



Overview [#overview]

Small displays with low resolution don't look pretty with automatically rendered fonts. A bitmap font provides
the solution, but it's necessary to convert the bitmap font (BDF) to a TTF.

Convert BDF to TTF [#convert-bdf-to-ttf]

BDF are bitmap fonts where fonts are not described in outlines but in pixels. BDF files can be used but
they must be converted into the TTF format using [mkttf`, which can be found
in this GitHub repository:  https://github.com/Tblue/mkttf .  This tool uses potrace to generate outlines from
the bitmap information. The bitmap itself will be embedded into the TTF as well. `lv\_font\_conv](https://github.com/lvgl/lv_font_conv/) uses
the embedded bitmap but it also needs the outlines. One might think you can use a fake MS Bitmap
only sfnt (ttf) (TTF without outlines) created by fontforge, but this will not work.

Install imagemagick, python3, python3-fontforge and potrace

On Ubuntu Systems, just type

```bash title="bash" lineNumbers=1
sudo apt install imagemagick python3-fontforge potrace
```

Clone mkttf

```bash title="bash" lineNumbers=1
git clone https://github.com/Tblue/mkttf
```

Read the mkttf docs.

Former versions of imagemagick needs the imagemagick call in front of convert, identify and so on.
But newer versions don't. So you might want to change 2 lines in `potrace-wrapper.sh` ---
open `potrace-wrapper.sh` and remove imagemagick from line 55 and line 64:

line 55

```bash title="bash" lineNumbers=1
wh=($(identify -format '%[width]pt %[height]pt' "${input?}"))
```

line 64

```bash title="bash" lineNumbers=1
convert "${input?}" -sample '1000%' - \
```

It might be necessary to change the mkttf.py script.

line 1

```bash title="bash" lineNumbers=1
#!/usr/bin/env python3
```

Example [#example]

```console title="console" lineNumbers=1
cd mkttf
./mkttf.py ./TerminusMedium-12-12.bdf
Importing bitmaps from 0 additional fonts...
Importing font `./TerminusMedium-12-12.bdf' into glyph background...
Processing glyphs...
Saving TTF file...
Saving SFD file...
Done!
```

The TTF `TerminusMedium-001.000.ttf` will be created from `./TerminusMedium-12-12.bdf`.

To create a font for LVGL:

```bash title="bash" lineNumbers=1
lv_font_conv --bpp 1 --size 12 --no-compress --font TerminusMedium-001.000.ttf --range 0x20-0x7e,0xa1-0xff --format lvgl -o terminus_1bpp_12px.c
```

| Field  | Description                                                                                            |
| ------ | ------------------------------------------------------------------------------------------------------ |
| `note` | use 1-bpp because we don't use anti-aliasing. It doesn't look sharp on displays with a low resolution. |