A package inspired by [1], implementing dithering algorithms that can be used with PIL/Pillow.
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.
pip install git+https://www.github.com/hbldh/hitherdither
Bayer dithering using a median cut palette:
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:
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 can be run with pytest:
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 ===========================
| [1] | (1, 2) Joel Yliluoma's arbitrary-palette positional dithering algorithm (http://bisqwit.iki.fi/story/howto/dither/jy/) |