Traceback (most recent call last):
  File "./test_load_texture1.py", line 19, in <module>
    imsave('model_pkr_out1.png',images[0])
  File "/home/chengfei/anaconda2/lib/python2.7/site-packages/skimage/io/_io.py", line 131, in imsave
    if is_low_contrast(arr):
  File "/home/chengfei/anaconda2/lib/python2.7/site-packages/skimage/exposure/exposure.py", line 501, in is_low_contrast
    image = rgb2gray(image)
  File "/home/chengfei/anaconda2/lib/python2.7/site-packages/skimage/color/colorconv.py", line 796, in rgb2gray
    rgb = _prepare_colorarray(rgb[..., :3])
  File "/home/chengfei/anaconda2/lib/python2.7/site-packages/skimage/color/colorconv.py", line 157, in _prepare_colorarray
    return dtype.img_as_float(arr)
  File "/home/chengfei/anaconda2/lib/python2.7/site-packages/skimage/util/dtype.py", line 336, in img_as_float
    return convert(image, np.float64, force_copy)
  File "/home/chengfei/anaconda2/lib/python2.7/site-packages/skimage/util/dtype.py", line 236, in convert
    raise ValueError("Images of type float must be between -1 and 1.")
ValueError: Images of type float must be between -1 and 1.