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Document the compress_type save option for PNG #10278

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radarhere merged 2 commits into from
Oct 22, 2026
Merged

Document the compress_type save option for PNG #10278

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Document the compress_type save option for PNG
qodelicious Oct 22, 2026
674c3c8
Defaults to Z_DEFAULT_STRATEGY for P mode images
radarhere Oct 22, 2026
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7 changes: 7 additions & 0 deletions docs/handbook/image-file-formats.rst
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Expand Up @@ -955,6 +955,13 @@ The :py:meth:`~PIL.Image.Image.save` method supports the following options:
When ``optimize`` option is True ``compress_level`` has no effect
(it is set to 9 regardless of a value passed).

**compress_type**
ZLIB compression strategy, one of the strategy constants from Python's
:py:mod:`zlib` module: ``zlib.Z_DEFAULT_STRATEGY`` (0), ``zlib.Z_FILTERED`` (1),
``zlib.Z_HUFFMAN_ONLY`` (2), ``zlib.Z_RLE`` (3) or ``zlib.Z_FIXED`` (4). For ``P``
images, defaults to ``zlib.Z_DEFAULT_STRATEGY`` (0). Otherwise defaults to
``zlib.Z_FILTERED`` (1).

**icc_profile**
The ICC Profile to include in the saved file.

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