BUG Raise exception for invalid input

luispedro · efiring · commit 8433eec428e7 · 2016-03-06T15:47:42.000-10:00
Arrays of non-uint8 types were assumed to be in 0..1 range. When this was not true and integer values were used, only the low-order bits were used, resulting in a mangled image. Now, an explicit exception is raised. Closes issue matplotlib#2499
diff --git a/lib/matplotlib/cm.py b/lib/matplotlib/cm.py
@@ -255,6 +255,8 @@ def to_rgba(self, x, alpha=None, bytes=False, norm=True):
                     xx = x
                 else:
                     raise ValueError("third dimension must be 3 or 4")
+                if xx.dtype != np.uint8 and xx.max() > 1:
+                    raise ValueError("image must be either uint8 or in the 0..1 range")
                 if bytes and xx.dtype != np.uint8:
                     xx = (xx * 255).astype(np.uint8)
                 if not bytes and xx.dtype == np.uint8:
