Merge pull request #2956 from pnuu/bugfix-cira-stretch-upcast

Fix cira stretch upcasting the data

satpy/enhancements/__init__.py

@@ -219,11 +219,12 @@ def cira_stretch(img, **kwargs):
 
 @exclude_alpha
 def _cira_stretch(band_data):
-    log_root = np.log10(0.0223)
+    dtype = band_data.dtype
+    log_root = np.log10(0.0223, dtype=dtype)
     denom = (1.0 - log_root) * 0.75
     band_data *= 0.01
     band_data = band_data.clip(np.finfo(float).eps)
-    band_data = np.log10(band_data)
+    band_data = np.log10(band_data, dtype=dtype)
     band_data -= log_root
     band_data /= denom
     return band_data

satpy/tests/enhancement_tests/test_enhancements.py

@@ -34,30 +34,55 @@
 
 def run_and_check_enhancement(func, data, expected, **kwargs):
     """Perform basic checks that apply to multiple tests."""
+    pre_attrs = data.attrs
+    img = _get_enhanced_image(func, data, **kwargs)
+
+    _assert_image(img, pre_attrs, func.__name__, "palettes" in kwargs)
+    _assert_image_data(img, expected)
+
+
+def _get_enhanced_image(func, data, **kwargs):
     from trollimage.xrimage import XRImage
 
-    pre_attrs = data.attrs
     img = XRImage(data)
     func(img, **kwargs)
 
+    return img
+
+
+def _assert_image(img, pre_attrs, func_name, has_palette):
+    assert isinstance(img.data, xr.DataArray)
     assert isinstance(img.data.data, da.Array)
+
     old_keys = set(pre_attrs.keys())
     # It is OK to have "enhancement_history" added
     new_keys = set(img.data.attrs.keys()) - {"enhancement_history"}
     # In case of palettes are used, _FillValue is added.
     # Colorize doesn't add the fill value, so ignore that
-    if "palettes" in kwargs and func.__name__ != "colorize":
+    if has_palette and func_name != "colorize":
         assert "_FillValue" in new_keys
         # Remove it from further comparisons
         new_keys = new_keys - {"_FillValue"}
     assert old_keys == new_keys
 
-    res_data_arr = img.data
-    assert isinstance(res_data_arr, xr.DataArray)
-    assert isinstance(res_data_arr.data, da.Array)
-    res_data = res_data_arr.data.compute()  # mimics what xrimage geotiff writing does
+
+def _assert_image_data(img, expected, dtype=None):
+    # Compute the data to mimic what xrimage geotiff writing does
+    res_data = img.data.data.compute()
     assert not isinstance(res_data, da.Array)
     np.testing.assert_allclose(res_data, expected, atol=1.e-6, rtol=0)
+    if dtype:
+        assert img.data.dtype == dtype
+        assert res_data.dtype == dtype
+
+
+def run_and_check_enhancement_with_dtype(func, data, expected, **kwargs):
+    """Perform basic checks that apply to multiple tests."""
+    pre_attrs = data.attrs
+    img = _get_enhanced_image(func, data, **kwargs)
+
+    _assert_image(img, pre_attrs, func.__name__, "palettes" in kwargs)
+    _assert_image_data(img, expected, dtype=data.dtype)
 
 
 def identical_decorator(func):
@@ -109,14 +134,15 @@ def _calc_func(data):
             exp_data = exp_data[np.newaxis, :, :]
         run_and_check_enhancement(_enh_func, in_data, exp_data)
 
-    def test_cira_stretch(self):
+    @pytest.mark.parametrize("dtype", [np.float32, np.float64])
+    def test_cira_stretch(self, dtype):
         """Test applying the cira_stretch."""
         from satpy.enhancements import cira_stretch
 
         expected = np.array([[
             [np.nan, -7.04045974, -7.04045974, 0.79630132, 0.95947296],
-            [1.05181359, 1.11651012, 1.16635571, 1.20691137, 1.24110186]]])
-        run_and_check_enhancement(cira_stretch, self.ch1, expected)
+            [1.05181359, 1.11651012, 1.16635571, 1.20691137, 1.24110186]]], dtype=dtype)
+        run_and_check_enhancement_with_dtype(cira_stretch, self.ch1.astype(dtype), expected)
 
     def test_reinhard(self):
         """Test the reinhard algorithm."""