imagequant 1.0.2

Image Quantization Library

Imagequant Python are bindings to allow using libimagequant from Python.

Libimagequant is a small, portable C library for high-quality conversion of RGBA images to 8-bit indexed-color (palette) images.

Install

From PyPI:

pip3 install imagequant

NOTE: you may require compilation tools to build the library if you system is not suitable for the precompiled wheels. On Debian / Ubuntu you can install the build dependencies with the following command:

sudo apt install build-essential python3-dev

Usage

With PIL / Pillow

from PIL import Image
import imagequant

input_image = Image.open("./example.png")
output_image = imagequant.quantize_pil_image(
    input_image,
    dithering_level=1.0,  # from 0.0 to 1.0
    max_colors=256,       # from 1 to 256
)
output_image.save("./out.png", format="PNG")

→

With Raw Data

import imagequant

# 2×2px image
IMAGE_DATA = (
    # | R | G | B | A |
    b"\xFF\x00\x00\xFF"  # red
    b"\x00\xFF\x00\xFF"  # lime
    b"\x00\x00\xFF\xFF"  # blue
    b"\xFF\xFF\xFF\xFF"  # white
)

output_image_data, output_palette = imagequant.quantize_raw_rgba_bytes(
    IMAGE_DATA,           # RGBA image data
    2, 2,                 # width, height
    dithering_level=1.0,  # from 0.0 to 1.0
    max_colors=256,       # from 1 to 256
)

# you can now encode image data and the palette in any image format...

Example output_image_data:

b'\x02\x03\x00\x01'

Example output_palette:

[0, 0, 255, 255, 255, 255, 255, 255, 255, 0, 0, 255, 0, 255, 0, 255, 0, 0, 0, 0, ...]
# color 0      | color 1           | color 2       | color 3       | color 4   | ...

Development of the Bindings

Clone the repository and get the submodules:

git clone https://github.com/wanadev/imagequant-python.git
cd imagequant-python
git submodule init
git submodule update

Install some dependencies (preferably in a virtualenv):

pip3 install nox cffi pillow

Build the binary part of the lib:

python imagequant/libimagequant_build.py

A .so file (or a .pyd file on Windows, or a .dylib file on MacOS) shoud now be present in the imagequant/ folder. You will not need to run this command again until you change something in imagequant/libimagequant.h or in libimagequant/*.{c,h}.

To check the coding style, you can run the lint with the following command:

nox -s lint

To run the tests, use the following command:

nox -s test

License

Imagequant Python is licensed under the BSD 3 Clause. See the LICENSE file for more information.

Libimagequant is dual-licensed:

• For Free/Libre Open Source Software it’s available under GPL v3 or later with additional copyright notices for older parts of the code.

• For use in closed-source software, AppStore distribution, and other non-GPL uses, you can obtain a commercial license.

Read its license terms for more information.

Changelog

• v1.0.2: Python 3.10 support and wheels

• v1.0.1: Fix encoding while reading the README in setup.py

• v1.0.0: Initial release with a minimal API.