ImageDraw.polygon is very slow when width > 1 #8976
Description
What did you do?
I'm generating maps from shapefiles. The full code is a bit too much to repeat here, and a reproducible sample is also tricky because of all the data needed. If desired I can produce a POC zip.
This is a cut-down version of the code:
img = Image.new('RGB', (self._view.width * RESIZE_FACTOR,
self._view.height * RESIZE_FACTOR),
self._background.as_int_tuple(255))
draw = ImageDraw.Draw(img)
for layer in self._layers:
# stuff to compute parameters
draw.polygon(coords2, outline = lc, width = lw, fill = fc)
# resize to smooth image
if RESIZE_FACTOR != 1:
img = img.resize((int(img.width / RESIZE_FACTOR),
int(img.height / RESIZE_FACTOR)),
resample = Image.Resampling.LANCZOS)
img.save(filename, 'PNG')What did you expect to happen?
When lw above (line width) is 1 this runs in 4 seconds. When it's 3 the code takes 5 minutes. That seems ... unnecessary?
Of course, the ImageDraw.polygon method is being worked hard here, but if it can do the thin line in 4 seconds ...
What are your OS, Python and Pillow versions?
- OS: MacOS 12.7.1
- Python: 3.13.3
- Pillow: 11.2.1 from pip
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Pillow 11.2.1
Python 3.13.3 (main, May 20 2025, 08:52:01) [Clang 14.0.0 (clang-1400.0.29.202)]
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Python executable is /usr/local/opt/python@3.13/bin/python3.13
System Python files loaded from /usr/local/opt/python@3.13/Frameworks/Python.framework/Versions/3.13
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Python Pillow modules loaded from /usr/local/lib/python3.13/site-packages/PIL
Binary Pillow modules loaded from /usr/local/lib/python3.13/site-packages/PIL
--------------------------------------------------------------------
--- PIL CORE support ok, compiled for 11.2.1
*** TKINTER support not installed
--- FREETYPE2 support ok, loaded 2.13.3
--- LITTLECMS2 support ok, loaded 2.17
--- WEBP support ok, loaded 1.5.0
*** AVIF support not installed
--- JPEG support ok, compiled for libjpeg-turbo 3.1.0
--- OPENJPEG (JPEG2000) support ok, loaded 2.5.3
--- ZLIB (PNG/ZIP) support ok, loaded 1.3.1
--- LIBTIFF support ok, loaded 4.7.0
--- RAQM (Bidirectional Text) support ok, loaded 0.10.1, fribidi 1.0.16, harfbuzz 11.0.1
*** LIBIMAGEQUANT (Quantization method) support not installed
--- XCB (X protocol) support ok
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