Make smoothing in gNCC optional (#390)

Author: eigenvivek

diffdrr/metrics.py

@@ -85,7 +85,10 @@ def __init__(self, sigma: float):
         self.filter.weight = torch.nn.Parameter(G, requires_grad=False)
 
     def forward(self, img):
-        x = gaussian_blur(img, 5, self.sigma)
+        x = img
+        if self.sigma > 0:
+            kernel_size = int(6 * self.sigma + 1) | 1
+            x = gaussian_blur(img, kernel_size, self.sigma)
         x = self.filter(x)
         return x
 

notebooks/api/05_metrics.ipynb

@@ -179,7 +179,10 @@
     "        self.filter.weight = torch.nn.Parameter(G, requires_grad=False)\n",
     "\n",
     "    def forward(self, img):\n",
-    "        x = gaussian_blur(img, 5, self.sigma)\n",
+    "        x = img\n",
+    "        if self.sigma > 0:\n",
+    "            kernel_size = int(6 * self.sigma + 1) | 1\n",
+    "            x = gaussian_blur(img, kernel_size, self.sigma)\n",
     "        x = self.filter(x)\n",
     "        return x"
    ]