Pillow/docs/reference/limits.rst

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Limits
------
This page is documentation to the various fundamental size limits in
the Pillow implementation.
Internal Limits
===============
* Image sizes cannot be negative. These are checked both in
``Storage.c`` and ``Image.py``
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* Image sizes may be 0. (Although not in 3.4)
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* Maximum pixel dimensions are limited to INT32, or 2^31 by the sizes
in the image header.
* Individual allocations are limited to 2GB in ``Storage.c``
* The 2GB allocation puts an upper limit to the xsize of the image of
either 2^31 for 'L' or 2^29 for 'RGB'
* Individual memory mapped segments are limited to 2GB in map.c based
on the overflow checks. This requires that any memory mapped image
is smaller than 2GB, as calculated by ``y*stride`` (so 2Gpx for 'L'
images, and .5Gpx for 'RGB'
* Any call to internal python size functions for buffers or strings
are currently returned as int32, not py_ssize_t. This limits the
maximum buffer to 2GB for operations like frombytes and frombuffer.
* This also limits the size of buffers converted using a
decoder. (decode.c:127)
Format Size Limits
==================
* ICO: Max size is 256x256
* Webp: 16383x16383 (underlying library size limit:
https://developers.google.com/speed/webp/docs/api)