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Merged
hugovk merged 1 commit into from
Aug 19, 2025
Merged

Document ImageFile.MAXBLOCK #9163

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1 change: 1 addition & 0 deletions docs/reference/ImageFile.rst
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Expand Up @@ -74,5 +74,6 @@ Constants
---------

.. autodata:: PIL.ImageFile.LOAD_TRUNCATED_IMAGES
.. autodata:: PIL.ImageFile.MAXBLOCK
.. autodata:: PIL.ImageFile.ERRORS
:annotation:
12 changes: 12 additions & 0 deletions src/PIL/ImageFile.py
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Expand Up @@ -46,6 +46,18 @@
logger = logging.getLogger(__name__)

MAXBLOCK = 65536
"""
By default, Pillow processes image data in blocks. This helps to prevent excessive use
of resources. Codecs may disable this behaviour with ``_pulls_fd`` or ``_pushes_fd``.

When reading an image, this is the number of bytes to read at once.

When writing an image, this is the number of bytes to write at once.
If the image width times 4 is greater, then that will be used instead.
Plugins may also set a greater number.

User code may set this to another number.
"""

SAFEBLOCK = 1024 * 1024

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