Kobo Font Fix

Overview

kobofix.py is a Python script designed to process TTF fonts for Kobo e-readers.

It generates a renamed font, fixes PANOSE information based on the filename, adjusts the baseline with the font-line utility, and adds a legacy kern table which allows the kepub engine for improved rendering of kerned pairs.

You can use this to modify or fix your own, legally acquired fonts (assuming you are permitted to do so).

Requirements

Python 3, FontTools, font-line.

You can install them like so:

pip3 install fonttools
pip3 install font-line

On macOS, if you're using the built-in version of Python (via Xcode), you may need to first add a folder to your PATH to make font-line available, like:

echo 'export PATH="$HOME/Library/Python/3.9/bin:$PATH"' >> ~/.zshrc
source ~/.zshrc

Usage

Open a terminal and navigate to the directory containing your font files.
Run the script with a glob pattern to include all TTF files:
```
python3 kobofix.py *.ttf
```
The default script will:
- Validate the file names (must end with -Regular, -Bold, -Italic or -BoldItalic so they're valid for Kobo devices).
- Process each font (e.g. "Lora" becomes "KF Lora").
- Apply kerning, rename, PANOSE adjustments, and baseline shift.
- Save output as KF_<original_filename>.

You can customize what the script does.

Customization

Generating KF fonts

This applies the KF prefix, applies 20 percent line spacing and adds a Kobo kern table. Ideal if you have an existing TrueType font and you want it on your Kobo device.

The --name parameter is used to change the name of the font family.

./kobofix.py --prefix KF --name="Fonty" --line-percent 20 *.ttf

Generating NV fonts

Tight spacing, with a custom font family name:

./kobofix.py --prefix NV --name="Fonty" --line-percent 20 --skip-kobo-kern *.ttf

Relaxed spacing, with a custom font family name:

./kobofix.py --prefix NV --name="Fonty" --line-percent 50 --skip-kobo-kern *.ttf

You can play around with --line-percent to see what works for you.

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