Force novice.Picture.from_size to return a uint8 image

Force Picure.from_size to return a uint8 image

Remove img_as_ubyte

skimage/novice/_novice.py

@@ -282,6 +282,7 @@ class Picture(object):
             color = color_dict[color]
         rgb_size = tuple(size) + (len(color),)
         array = np.ones(rgb_size, dtype=np.uint8) * color
+        array = array.astype(np.uint8)
 
         # Force RGBA internally (use max alpha)
         if array.shape[-1] == 3:

skimage/novice/tests/test_novice.py

@@ -86,6 +86,8 @@ def test_pixel_rgb():
     pixel.rgb = np.arange(4)
     assert_equal(pixel.rgb, np.arange(3))
 
+    assert pic.array.dtype == np.uint8
+
 
 def test_pixel_rgba():
     pic = novice.Picture.from_size((3, 3), color=(10, 10, 10))