fix IOError: image file truncated” with big image

[JirenJin]

If the image size is too large, then such error will occur: OSError: image file is truncated (13 bytes not processed).

The solution I found from stackoverflow: https://stackoverflow.com/questions/12984426/python-pil-ioerror-image-file-truncated-with-big-images.

I tested it and it actually works.

[Hakuyume]

Thank you. Could you add tests for such large images?