Add test for reading and writing uint16 TIFFs.

Tests/test_file_tiff.py

@@ -463,6 +463,13 @@ class TestFileTiff(PillowTestCase):
         im2 = hopper()
         self.assert_image_similar(im, im2, 5)
 
+    def test_open_tiff_uint16(self):
+        # Test an image of all '0' values
+        pixel_value = 0x1234
+        infile = "Tests/images/uint16_1_{}.tif".format(pixel_value)
+        im = Image.open(infile)
+        self.assertEqual(im.getpixel((0, 0)), pixel_value)
+
 
 if __name__ == '__main__':
     unittest.main()

Tests/test_numpy.py

@@ -110,6 +110,21 @@ class TestNumpy(PillowTestCase):
         self._test_img_equals_nparray(img, np_img)
         self.assertEqual(np_img.dtype, numpy.dtype('<u2'))
 
+    def test_save_tiff_uint16(self):
+        '''
+        Open a single-channel uint16 greyscale image and verify that it can be saved without
+        losing precision.
+        '''
+        tmpfile = self.tempfile("temp.tif")
+        pixel_value = 0x1234
+        filename = "Tests/images/uint16_1_4660.tif"
+        a = numpy.array([pixel_value] * 100, dtype=numpy.uint16)
+        a.shape = TestNumpy.TEST_IMAGE_SIZE
+        Image.fromarray(a).save(tmpfile)
+        im_test = Image.open(tmpfile)
+        im_good = Image.open(filename)
+        self.assert_image_equal(im_good, im_test)
+
     def test_to_array(self):
 
         def _to_array(mode, dtype):