hp.load does not work

[lindsey]

my code works with provided images that is preloaded with metadata (i.e.get_example_data('image0001.yaml')

but it doesn't let me load my own images in the directory.

In[2]: import holopy as hp
optics = hp.core.Optics(wavelen=.660, index=1.33,
polarization=[1.0, 0.0])

In[3]: holo = hp.load('1.tif', spacing = .1, optics = optics)

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/IPython/core/interactiveshell.py", line 2820, in run_code
    exec code_obj in self.user_global_ns, self.user_ns
  File "<ipython-input-3-153511853999>", line 1, in <module>
    holo = hp.load('1.tif', spacing = .1, optics = optics)
  File "/usr/local/lib/python2.7/dist-packages/holopy/core/io/io.py", line 94, in load
    loaded = load_image(inf, spacing=spacing, optics=optics, channel=channel)
  File "/usr/local/lib/python2.7/dist-packages/holopy/core/io/image_file_io.py", line 157, in load_image
    metadata = json.loads(description)
  File "/usr/lib/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
TypeError: expected string or buffer

thank you so much for your help!