Does work for 1bit compressed TIFF about pylibtiff HOT 9 CLOSED

I wrote a patch to read group4 binary images... it might not work for other 
compression schemes, and gives an image with inverted colors.

It works for my images! Thanks for the patch!

Even if it does not provide complete support for 1bit images
(no write support, the returned array is actually 8 bit array
because numpy does not have int1 type available)
I have applied the patch (with slight modification) to svn repo
because the patch is simple and it works for some applications.

There is no int1 type available, but there is numpy.bool for binary vectors...

Sure, but numpy.bool has 8 bits, not 1, and thus it is equivalent to numpy.int8.
This makes writing numpy.bool arrays as 1 bit arrays tricky (need to use
bittools extension module to convert 8bit arrays to 1bit arrays before calling 
WriteStrip).

~# python3 test_tiff.py scanned_bw_multi_page.tif
TIFFReadDirectory: Warning, Unknown field with tag 33579 (0x832b) encountered.
TIFFReadDirectory: Warning, Unknown field with tag 33580 (0x832c) encountered.
Traceback (most recent call last):
  File "test_tiff.py", line 9, in <module>
    image = tif.read_image()
  File "/usr/local/lib/python3.7/dist-packages/libtiff/libtiff_ctypes.py", line 570, in read_image
    typ = self.get_numpy_type(bits, sample_format)
  File "/usr/local/lib/python3.7/dist-packages/libtiff/libtiff_ctypes.py", line 526, in get_numpy_type
    raise NotImplementedError("bits = {0:d}".format(bits))
NotImplementedError: bits = 1