This page is documentation to the various fundamental size limits in the Pillow implementation.
Image sizes cannot be negative. These are checked both in
Image sizes may be 0. (Although not in 3.4)
Maximum pixel dimensions are limited to INT32, or 2^31 by the sizes in the image header.
Individual allocations are limited to 2GB in
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)