Fixes for when no background is present.

lensless/utils/dataset.py

@@ -1565,20 +1565,26 @@ def _get_images_pair(self, idx):
 
             if len(background_np.shape) == 2:
                 warnings.warn(f"Converting background[{idx}] to RGB")
-                background_np = np.stack([background_np] * 3, axis=2) if not None else None
+                background_np = (
+                    np.stack([background_np] * 3, axis=2) if background_np is not None else None
+                )
             elif len(background_np.shape) == 3:
                 pass
 
         # convert to float
         if lensless_np.dtype == np.uint8:
             lensless_np = lensless_np.astype(np.float32) / 255
             lensed_np = lensed_np.astype(np.float32) / 255
-            background_np = background_np.astype(np.float32) / 255 if not None else None
+            background_np = (
+                background_np.astype(np.float32) / 255 if background_np is not None else None
+            )
         else:
             # 16 bit
             lensless_np = lensless_np.astype(np.float32) / 65535
             lensed_np = lensed_np.astype(np.float32) / 65535
-            background_np = background_np.astype(np.float32) / 65535 if not None else None
+            background_np = (
+                background_np.astype(np.float32) / 65535 if background_np is not None else None
+            )
 
         # downsample if necessary
         if self.downsample_lensless != 1.0:
@@ -1591,13 +1597,13 @@ def _get_images_pair(self, idx):
                     factor=1 / self.downsample_lensless,
                     interpolation=cv2.INTER_NEAREST,
                 )
-                if not None
+                if background_np is not None
                 else None
             )
 
         lensless = lensless_np
         lensed = lensed_np
-        background = background_np if not None else None
+        background = background_np if background_np is not None else None
 
         if self.simulator is not None:
             # convert to torch
@@ -1640,7 +1646,7 @@ def __getitem__(self, idx):
         # to torch
         lensless = torch.from_numpy(lensless)
         lensed = torch.from_numpy(lensed)
-        background = torch.from_numpy(background) if not None else None
+        background = torch.from_numpy(background) if background is not None else None
         # If [H, W, C] -> [D, H, W, C]
         if len(lensless.shape) == 3:
             lensless = lensless.unsqueeze(0)