FIX: Better

Author: larsoner

nibabel/nifti1.py

@@ -2443,7 +2443,7 @@ def _get_analyze_compat_dtype(arr):
         return np.dtype('int16' if arr.max() <= np.iinfo(np.int16).max else 'int32')
 
     mn, mx = arr.min(), arr.max()
-    if arr.dtype.kind == 'i':
+    if arr.dtype.kind in 'iu':
         info = np.iinfo('int32')
         if mn >= info.min and mx <= info.max:
             return np.dtype('int32')

nibabel/tests/test_spm99analyze.py

@@ -328,7 +328,8 @@ def test_no_scaling(self, in_dtype, supported_dtype):
         inter = 10 if hdr.has_data_intercept else 0
 
         mn_in, mx_in = _dt_min_max(in_dtype)
-        arr = np.array([mn_in, -1, 0, 1, 10, mx_in], dtype=in_dtype)
+        mn = -1 if np.dtype(in_dtype).kind != 'u' else 0
+        arr = np.array([mn_in, mn, 0, 1, 10, mx_in], dtype=in_dtype)
         img = img_class(arr, np.eye(4), hdr)
         img.set_data_dtype(supported_dtype)
         # Setting the scaling means we don't calculate it later