A Python GUI for halftoning

hopfer is a Python-based GUI application that implements a wide range of halftoning algorithms from scratch primarily meant for printmaking purposes.

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Table of contents

• Introduction
• Features
• Requirements
• Installation
• Acknowledgments

Introduction

hopfer is a digital halftoning tool built with Qt6 for the GUI, while leveraging NumPy and Numba for high-performance halftoning.

Originally developed as part of my PhD research on digital halftoning for analog printmaking techniques, hopfer is designed primarily for this purpose. While it may have applications in image compression and visual effects, these are not its main focus.

At present, hopfer does not support palette-based halftoning or multi-level dithering, and there are no plans to add these features.

Features

• A variety of halftoning algorithms, including:
  • Fixed threshold
  • Local thresholds
  • Random dithering
  • Bayer dithering
  • Clustered dot halftoning
  • Error diffusion dithering
  • Variable error diffusion dithering
• Basic non-destructive image editing tools, such as:
  • Rotation
  • Brightness & contrast
  • Gaussian blurring
  • Denoising
  • Sharpening
• Support for a wide range of image formats, including:
  • PNG, JPEG, BMP, TIFF, WebP and more (anything supported by OpenCV)

Requirements

Not sure yet.

Installation

1. Clone the repository

git clone https://github.com/crunchpaste/hopfer

2. Navigate to the project directory

cd hopfer

3. Install the dependencies (preferably in a venv)

pip install -r requirements.txt

4. Run it

python src/hopfer.py

Optional: Compile to a static binary

Despite depending on numba you can still compile hopfer to a single static binary using nuitka. To do so:

Compile all numba functions to a static binary

python src/algorithm_compiler.py

Install nuitka (preferably in a venv)

pip install nuitka

Compile the whole project to a static binary.

nuitka --standalone --onefile --include-data-dir=res=res --nofollow-import-to=numba --enable-plugins=pyside6 src/hopfer.py

Acknowledgments

The project relies on the following awesome open-source libraries. I extend my thanks to their maintainers and contributors!

Core

• numpy: GitHub Link

  The fundamental package for scientific computing with Python.

• Numba: GitHub Link

  A Just-In-Time compiler for numerical functions in Python.

• opencv-python: GitHub Link

  Used for image processing and encoding/decoding.

• requests: GitHub Link

  A simple, yet elegant, HTTP library.

User Interface

• PySide6: Documentation Link

  The official Python bindings for the Qt framework, used to build the GUI.

• PyQt-Frameless-Window: GitHub Link

  Enables the creation of custom frameless windows.

• superqt: GitHub Link

  "missing" widgets and components for PyQt/PySide

System

• makeself: GitHub Link

  Used for creating the Linux installer.

• Nuitka: Website

  Used for compiling the application into an executable.

• platformdirs: GitHub Link

  Used for determining standard, cross-platform directories for storing image and configuration data.

• setproctitle: GitHub Link

  Allows a process to change its title.

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Enjoy halftoning!