Broken quantized png #9128
Description
What did you do?
from PIL import Image
img = Image.open('plusx.jpg')
print(f"Original size: {img.size}, mode: {img.mode}")
resized = img.resize((img.width//2, img.height//2), Image.Resampling.LANCZOS)
quantized = resized.quantize(colors=256, method=3)
print(f"Quantized mode: {quantized.mode}, palette colors: {len(quantized.getpalette())//3}")
quantized.save('output_quantized.png')
print("Saved: output_quantized.png")What did you expect to happen?
saved a nice quantized png
What actually happened?
saved a broken quantized png
What are your OS, Python and Pillow versions?
- OS: macOS 26 Public Beta
- Python: [email protected]
- Pillow: 11.3
/opt/homebrew/Cellar/[email protected]/3.13.3_1/bin/python3 -m PIL --report
--------------------------------------------------------------------
Pillow 11.3.0
Python 3.13.3 (main, Apr 8 2025, 13:54:08) [Clang 17.0.0 (clang-1700.0.13.3)]
--------------------------------------------------------------------
Python executable is /opt/homebrew/opt/[email protected]/bin/python3.13
System Python files loaded from /opt/homebrew/opt/[email protected]/Frameworks/Python.framework/Versions/3.13
--------------------------------------------------------------------
Python Pillow modules loaded from /opt/homebrew/lib/python3.13/site-packages/PIL
Binary Pillow modules loaded from /opt/homebrew/lib/python3.13/site-packages/PIL
--------------------------------------------------------------------
--- PIL CORE support ok, compiled for 11.3.0
*** 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 ok, loaded 1.3.0
--- JPEG support ok, compiled for libjpeg-turbo 3.1.1
--- OPENJPEG (JPEG2000) support ok, loaded 2.5.3
--- ZLIB (PNG/ZIP) support ok, loaded 1.2.12
--- LIBTIFF support ok, loaded 4.7.0
--- RAQM (Bidirectional Text) support ok, loaded 0.10.2
--- LIBIMAGEQUANT (Quantization method) support ok, loaded 4.2.2
--- XCB (X protocol) support okOrigin Jpeg:
https://demopub.s3.us-west-000.backblazeb2.com/plusx.jpg
Output Png:
