pyoxipng

9.1.1 verified Sat May 09 auth: no python

Python wrapper for oxipng, a multithreaded PNG optimizer. Version 9.1.1 supports Python >=3.8 and is actively maintained. Releases follow oxipng upstream closely, typically every few months.

pip install pyoxipng

Common errors

error TypeError: expected bytes, got str ↓

cause Passing a file path string instead of bytes to optimize_png.

fix

Open the file in binary mode: with open('file.png', 'rb') as f: data = f.read().

error AttributeError: module 'pyoxipng' has no attribute 'optimize_png' ↓

cause Old version (pre-7.0) had different API or the module is not installed correctly.

fix

Upgrade to 9.1.1: pip install --upgrade pyoxipng and use from pyoxipng import optimize_png.

error NameError: name 'optimize_png' is not defined ↓

cause Forgot to import the function correctly.

fix

Add from pyoxipng import optimize_png at the top of the script.

Warnings

gotcha optimize_png accepts bytes, not a file path. Passing a file path will fail silently or raise TypeError. ↓

fix Open the file in binary read mode and pass bytes.

breaking Version 7.0.0 changed the return type from (bytes, bool) to bytes. The second element (whether the image was changed) was removed. ↓

fix Update code from `result, changed = optimize_png(data)` to `result = optimize_png(data)`. Use `if result != data:` to check if optimized.

deprecated The `level` parameter in optimize_png is deprecated since 8.0.0, use `opts` dict instead. ↓

fix Replace `optimize_png(data, level=6)` with `optimize_png(data, opts=dict(level=6))`.

Imports

optimize_png
wrong
```
import oxipng
```
correct
```
from pyoxipng import optimize_png
```
oxipng is the Rust crate; the Python package is pyoxipng.

Quickstart

Read a PNG from file, optimize it in memory, and save the result.

from pyoxipng import optimize_png

with open('input.png', 'rb') as f:
    data = f.read()
result = optimize_png(data)
with open('output.png', 'wb') as f:
    f.write(result)