BF: fix conversion of bit images to numpy arrays

Numpy cannot form arrays from bits.  To convert bit images to numpy,
convert bits to bytes.

From suggestion by Alexander Karpinsky, with thanks.

Fixes gh-350.

PIL/Image.py

@@ -246,7 +246,7 @@ else:
 
 _MODE_CONV = {
     # official modes
-    "1": ('|b1', None),  # broken
+    "1": ('|b1', None),  # Bits need to be extended to bytes
     "L": ('|u1', None),
     "LA": ('|u1', 2),
     "I": (_ENDIAN + 'i4', None),
@@ -615,17 +615,21 @@ class Image(object):
         self.save(b, 'PNG')
         return b.getvalue()
 
-    def __getattr__(self, name):
-        if name == "__array_interface__":
-            # numpy array interface support
-            new = {}
-            shape, typestr = _conv_type_shape(self)
-            new['shape'] = shape
-            new['typestr'] = typestr
+    @property
+    def __array_interface__(self):
+        # numpy array interface support
+        new = {}
+        shape, typestr = _conv_type_shape(self)
+        new['shape'] = shape
+        new['typestr'] = typestr
+        new['version'] = 3
+        if self.mode == '1':
+            # Binary images need to be extended from bits to bytes
+            # See: https://github.com/python-pillow/Pillow/issues/350
+            new['data'] = self.tobytes('raw', 'L')
+        else:
             new['data'] = self.tobytes()
-            new['version'] = 3
-            return new
-        raise AttributeError(name)
+        return new
 
     def __getstate__(self):
         return [

Tests/test_image_array.py

@@ -25,13 +25,26 @@ class TestImageArray(PillowTestCase):
         self.assertEqual(test("RGBX"), (3, (100, 128, 4), '|u1', 51200))
 
     def test_fromarray(self):
+
+        class Wrapper(object):
+            """ Class with API matching Image.fromarray """
+
+            def __init__(self, img, arr_params):
+                self.img = img
+                self.__array_interface__ = arr_params
+
+            def tobytes(self):
+                return self.img.tobytes()
+
         def test(mode):
             i = im.convert(mode)
             a = i.__array_interface__
-            a["strides"] = 1  # pretend it's non-contiguous
-            i.__array_interface__ = a  # patch in new version of attribute
-            out = Image.fromarray(i)
+            a["strides"] = 1  # pretend it's non-contigous
+            # Make wrapper instance for image, new array interface
+            wrapped = Wrapper(i, a)
+            out = Image.fromarray(wrapped)
             return out.mode, out.size, list(i.getdata()) == list(out.getdata())
+
         # self.assertEqual(test("1"), ("1", (128, 100), True))
         self.assertEqual(test("L"), ("L", (128, 100), True))
         self.assertEqual(test("I"), ("I", (128, 100), True))

Tests/test_numpy.py

@@ -117,6 +117,15 @@ class TestNumpy(PillowTestCase):
         self._test_img_equals_nparray(img, np_img)
         self.assertEqual(np_img.dtype, numpy.dtype('<u2'))
 
+    def test_1bit(self):
+        # Test that 1-bit arrays convert to numpy and back
+        # See: https://github.com/python-pillow/Pillow/issues/350
+        arr = numpy.array([[1, 0, 0, 1, 0], [0, 1, 0, 0, 0]], 'u1')
+        img = Image.fromarray(arr * 255).convert('1')
+        self.assertEqual(img.mode, '1')
+        arr_back = numpy.array(img)
+        numpy.testing.assert_array_equal(arr, arr_back)
+
     def test_save_tiff_uint16(self):
         '''
         Open a single-channel uint16 greyscale image and verify that it can be saved without