OCR application for reading manga in Japanese, made for AJATTers🇯🇵

Lancet

Lancet is an OCR application for reading manga in Japanese. It uses PyTorch models to recognize Japanese text in images. Lancet works best with Goldendict-ng or Rikaitan.

https://github.com/user-attachments/assets/8859adac-1bd8-435a-9c81-945f875dc205

User Guide

Prerequisites:

• Goldendict for looking up words in Japanese dictionaries.
• nsxiv for reading manga.
• Recommended: i3wm, dwm, or any X11-based WM or DE (i.e. not Wayland).

Launch Goldendict, then open a manga folder in nsxiv. Start Lancet and wait for the OCR model to load. Press the OCR shortcut (default Alt+O) to show the snipping window, then drag and hold the mouse to perform OCR.

Lancet adds an icon to the system tray. Right‑click the icon to access actions, including Preferences, where you can change the OCR shortcut.

Installation

All operating systems

Install via pipx from pypi.

pipx install ajt-lancet

The lancet executable will be available in your $PATH.

[!NOTE] On Windows-like systems, you may need to add the folder containing the lancet executable to your $PATH manually.

[!NOTE] If you don't have the required python version, install it first with hatch.

hatch python install 3.13
pipx install ajt-lancet --python ~/.local/share/hatch/pythons/3.13/python/bin/python

Windows-like operating systems

Download lancet-windows.exe.

GNU/Linux

Download lancet-gnulinux.

System Requirements

Lancet depends on large Python libraries. pipx installs everything in an isolated location (~/.local/share/pipx) so you can cleanly uninstall with pipx uninstall later. The PyTorch models are downloaded from HuggingFace and saved to ~/.cache/huggingface.

• Disk space: ~8 GiB (PyTorch and dependencies)
• RAM: at least 2 GiB

Wayland support

Wayland support has been tested on Sway 1.11. Wayland support is incomplete. It works best on Hyprland and Sway, but on other compositors you may face issues if you have multiple monitors. 🙏 Please suggest improvements via pull requests on GitHub.

Upgrading

Running pipx upgrade upgrades lancet to the latest version.

pipx upgrade ajt-lancet

Running pipx upgrade-all upgrades all packages installed with pipx.

pipx upgrade-all

Development Setup

Since Ajatt-Tools is a distributed effort, we highly welcome new contributors! Install the project in development mode to easily test and commit your changes using hatch.

• Clone the repo.

• Install hatch:

  pipx install hatch
  pipx upgrade hatch
  

• CD into the repo and run:

  hatch shell
  

• Inside the hatch shell run:

  pip install -e .
  

• To run the app, run:

  hatch run lancet
  

Try these libre code editors with python support:

• pycharm-community-edition
• vscodium

Autostart

Add the lancet command to your autostart so Lancet launches at login.

Here's an example for i3wm:

exec --no-startup-id lancet

System keyboard shortcuts

On some setups (like Wayland), applications can't register global keyboard shortcuts, so Lancet's shortcuts won't work. You can define shortcuts in your Wayland compositor instead.

Below is an example for Sway. Add the following to your ~/.config/sway/config:

# Run OCR
bindsym $mod+o          exec lancet ocr
# Run OCR with the speech-bubble detector
bindsym $mod+Shift+o    exec lancet ocr --detect
# Take a screenshot
bindsym $mod+Print      exec lancet screenshot

Announcements

1. Sunsetting Transformers OCR
2. Meet Lancet