Mask out invalid pixels in the polar view

hexrd/projections/polar.py

@@ -6,6 +6,7 @@
     _project_on_detector_cylinder,
     _project_on_detector_plane,
 )
+from hexrd.utils.panel_buffer import panel_buffer_as_2d_array
 
 
 class PolarView:
@@ -325,10 +326,25 @@ def _warp_image_from_coordinate_map(
             coordinate_map: dict[str, dict[str, np.ndarray]],
             pad_with_nans: bool = False,
             do_interpolation=True) -> np.ma.MaskedArray:
+
+        panel_buffer_fill_value = np.nan
         img_dict = dict.fromkeys(self.detectors)
         nan_mask = None
         for detector_id, panel in self.detectors.items():
-            img = image_dict[detector_id]
+            # Make a copy since we may modify
+            img = image_dict[detector_id].copy()
+
+            # Before warping, mask out any pixels that are invalid,
+            # so that they won't affect the results.
+            buffer = panel_buffer_as_2d_array(panel)
+            if (np.issubdtype(type(panel_buffer_fill_value), np.floating) and
+                    not np.issubdtype(img.dtype, np.floating)):
+                # Convert to float. This is especially important
+                # for nan, since it is a float...
+                img = img.astype(float)
+
+            img[~buffer] = panel_buffer_fill_value
+
             xypts = coordinate_map[detector_id]['xypts']
             on_panel = coordinate_map[detector_id]['on_panel']
 

hexrd/utils/panel_buffer.py

@@ -0,0 +1,30 @@
+import numpy as np
+
+from hexrd.instrument.detector import Detector
+
+
+def panel_buffer_as_2d_array(panel: Detector) -> np.ndarray:
+    # Take whatever the panel buffer is and convert it to a 2D array
+    if panel.panel_buffer is None:
+        # Just make a panel buffer with all True values
+        return np.ones(panel.shape, dtype=bool)
+    elif panel.panel_buffer.shape == (2,):
+        # The two floats are specifying the borders in mm for x and y.
+        # Convert to pixel borders. Swap x and y so we have i, j in pixels.
+        borders = np.round([
+            panel.panel_buffer[1] / panel.pixel_size_row,
+            panel.panel_buffer[0] / panel.pixel_size_col,
+        ]).astype(int)
+
+        # Convert to array
+        panel_buffer = np.zeros(panel.shape, dtype=bool)
+
+        # We can't do `-borders[i]` since that doesn't work for 0,
+        # so we must do `panel.shape[i] - borders[i]` instead.
+        panel_buffer[borders[0]:panel.shape[0] - borders[0],
+                     borders[1]:panel.shape[1] - borders[1]] = True
+        return panel_buffer
+    elif panel.panel_buffer.ndim == 2:
+        return panel.panel_buffer
+
+    raise NotImplementedError(panel.panel_buffer.ndim)

tests/test_polar_view.py

@@ -72,9 +72,7 @@ def test_polar_view(
     img = img.filled(np.nan)
 
     # Verify that the image is identical to a reference image
-    ref = np.load(
-        test_data_dir / 'test_polar_view_expected.npy', allow_pickle=True
-    )
+    ref = np.load(test_data_dir / 'test_polar_view_expected.npy')
     assert np.allclose(img, ref, equal_nan=True)
 
     # Also generate it using the cache