https://github.com/hbldh/hitherdither

Dithering algorithms for arbitrary palettes in PIL
https://github.com/hbldh/hitherdither

dithering dithering-algorithms dithering-images pil pillow

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Dithering algorithms for arbitrary palettes in PIL

• Host: GitHub
• URL: https://github.com/hbldh/hitherdither
• Owner: hbldh
• License: mit
• Created: 2016-09-13T10:02:01.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2023-09-18T14:16:25.000Z (about 1 year ago)
• Last Synced: 2024-11-07T16:51:09.033Z (8 days ago)
• Topics: dithering, dithering-algorithms, dithering-images, pil, pillow
• Language: Python
• Homepage:
• Size: 61.5 KB
• Stars: 206
• Watchers: 8
• Forks: 21
• Open Issues: 5
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

        
hitherdither

============

|Build Status| |Coverage Status|

A package inspired by [1]_, implementing dithering algorithms that can be used with 

`PIL/Pillow `_. 

Description

-----------

This module is a small extension to `PIL/Pillow `_, adding

a more managable palette object and several dithering algorithms:

* Error diffusion dithering

    - Floyd-Steinberg

    - Jarvis-Judice-Ninke

    - Stucki

    - Burkes

    - Sierra3 

    - Sierra2

    - Sierra-2-4A

    - Stevenson-Arce

    - Atkinson

* Standard ordered dithering

    - Bayer matrix

    - Cluster dot matrix

    - Arbitrary square threshold matrix (not implemented yet)

* Yliluoma's ordered dithering (see [1]_)

    - Algorithm 1 

    - Algorithm 2 (not implemented yet)

    - Algorithm 3 (not implemented yet)

The dithering algorithms are applicable for arbitrary palettes and for both

RGB and greyscale images.

Installation

------------

::

    pip install git+https://www.github.com/hbldh/hitherdither

Usage

-----

Bayer dithering using a median cut palette:

.. code:: python

   from PIL import Image

   import hitherdither

   img = Image.open('image.jpg')

   palette = hitherdither.palette.Palette.create_by_median_cut(img)

   img_dithered = hitherdither.ordered.bayer.bayer_dithering(

       img, palette, [256/4, 256/4, 256/4], order=8)

`Yliluoma's Algorithm 1 `_

using a predefined palette:

.. code:: python

   from PIL import Image

   import hitherdither

   palette = hitherdither.palette.Palette(

       [0x080000, 0x201A0B, 0x432817, 0x492910,

        0x234309, 0x5D4F1E, 0x9C6B20, 0xA9220F,

        0x2B347C, 0x2B7409, 0xD0CA40, 0xE8A077,

        0x6A94AB, 0xD5C4B3, 0xFCE76E, 0xFCFAE2]

   )

   img = Image.open('image.jpg')

   img_dithered = hitherdither.ordered.yliluoma.yliluomas_1_ordered_dithering(

       img, palette, order=8)

Tests

~~~~~

Tests can be run with `pytest `_:

.. code:: sh

    hbldh@devbox:~/Repos/hitherdither$ py.test tests

    ============================= test session starts ==============================

    platform linux -- Python 3.5.2, pytest-3.0.2, py-1.4.31, pluggy-0.3.1

    rootdir: /home/hbldh/Repos/hitherdither, inifile: 

    collected 13 items 

    tests/test_bayer.py ...

    tests/test_palette.py ..........

    ========================== 13 passed in 0.11 seconds ===========================

References

----------

.. [1] Joel Yliluoma's arbitrary-palette positional dithering algorithm (http://bisqwit.iki.fi/story/howto/dither/jy/)

.. |Build Status| image:: https://github.com/hbldh/hitherdither/workflows/Build%20and%20Test/badge.svg

   :target: https://github.com/hbldh/hitherdither/actions?query=workflow%3A%22Build+and+Test%22

   :alt: Build and Test

.. |Coverage Status| image:: https://coveralls.io/repos/github/hbldh/hitherdither/badge.svg?branch=master

   :target: https://coveralls.io/github/hbldh/hitherdither?branch=master