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.

Anki screenshots

Lancet can attach a selected screen region to the Image field of the newest Anki note added within the last day. This replaces a separate screenshot utility for image-card creation.

1. Install and enable AnkiConnect, then launch Anki.

2. Create or add the target note.

3. Press Alt+I (the default shortcut), choose the screen region, and Lancet appends the image to that note's Image field.

   Finish active Browser edits before attaching an image. AnkiConnect cannot synchronously confirm that the Browser has saved pending editor changes.

Preferences has an Anki tab with the AnkiConnect URL, optional API key, target field, maximum image width/height, quality, and output format. The shortcut can be changed on the Main tab with Lancet's other shortcuts. Width and height are maximum bounds. 0 leaves an axis unconstrained, and images are never enlarged. The API key is masked in Preferences but stored in Lancet's plaintext JSON configuration file. On POSIX systems, Lancet writes that file with owner-only permissions. Literal localhost and numeric loopback AnkiConnect endpoints bypass HTTP_PROXY and HTTPS_PROXY. Custom remote endpoints retain normal proxy behavior. The field separator controls the HTML placed before each appended image. It defaults to <br> and may be empty.

Executable overrides

"Preferences" > "Advanced" lets you set the GoldenDict executable. Leave it empty to use automatic discovery through your system PATH.

Installation

All operating systems

Install via pipx from pypi.

pipx install ajt-lancet

The lancet executable will be available in your $PATH.

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: The example also works for i3wm (~/.config/i3/config).

# Run OCR
bindsym --release $mod+o          exec lancet ocr
# Run OCR with the speech-bubble detector
bindsym --release $mod+Shift+o    exec lancet ocr --detect
# Take a screenshot
bindsym --release $mod+Print      exec lancet screenshot
# Attach a selected screen region to the most recently added Anki note.
bindsym --release $mod+i          exec lancet screenshot --add-to-anki

Announcements

1. Sunsetting Transformers OCR
2. Meet Lancet