Skip to content

Latest commit

 

History

History
135 lines (95 loc) · 3.06 KB

README.md

File metadata and controls

135 lines (95 loc) · 3.06 KB

OCR Native Host for Kindle Auto Reader

This native messaging host enables offline OCR processing of captured PDFs using OCRmyPDF with Apple Vision Framework for superior Japanese text recognition.

Requirements

  • macOS 11.0 or later (Apple Silicon or Intel)
  • Python 3.9 or later
  • Google Chrome browser

Installation

Step 1: Install System Dependencies (Homebrew)

# Install Homebrew if not already installed
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

# Install OCRmyPDF and Tesseract
brew install ocrmypdf tesseract tesseract-lang

Step 2: Install Python Dependencies

cd native_host

# Install AppleOCR plugin and dependencies
pip3 install --user -r requirements.txt

Or manually:

pip3 install --user ocrmypdf-appleocr

Step 3: Run the Install Script

./install_macos.sh

This script will:

  1. Prompt for your Chrome extension ID
  2. Install the native messaging manifest
  3. Configure the host script
  4. Verify all dependencies are installed

Finding Your Extension ID

  1. Open Chrome and go to chrome://extensions/
  2. Enable "Developer mode" (toggle in top-right)
  3. Find "Auto Page Capture to PDF"
  4. Copy the 32-character ID shown below the extension name

Verification

After installation, verify everything works:

  1. Reload the extension in Chrome
  2. Open extension Options → OCR tab
  3. Should show "Dependencies OK" with version info

OCR Engines

The host supports two OCR engines:

Engine Best For Notes
Apple Vision (default) Japanese, CJK languages Uses macOS native OCR, better accuracy
Tesseract Fallback option Open-source, more language support

Files

File Description
ocr_host.py Main native messaging host script
install_macos.sh Installation script for macOS
requirements.txt Python dependencies
com.kindle_auto_reader.ocr_host.json Native messaging manifest template

Logs

OCR processing logs are written to:

~/.kindle-auto-reader/ocr.log

Troubleshooting

"Dependencies missing" error

  1. Ensure Homebrew packages are installed:

    brew install ocrmypdf tesseract tesseract-lang

  2. Ensure Python packages are installed:

    pip3 install --user ocrmypdf-appleocr

  3. Re-run the install script:

    ./install_macos.sh

"Native host has exited" error

Check the log file for details:

cat ~/.kindle-auto-reader/ocr.log

Common causes:

  • Python path issues (script updates shebang automatically)
  • Missing dependencies in Chrome's restricted PATH

OCR output has broken characters

  • Ensure you're using "Apple Vision" engine (not Tesseract)
  • Apple Vision provides much better Japanese text recognition

Uninstallation

To remove the native host:

rm ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.kindle_auto_reader.ocr_host.json

To also remove Python packages:

pip3 uninstall ocrmypdf-appleocr