Fix corner finding failures

* Remove image dilation step
* Implement dynamically sized Gaussian filter box using sqrt(2) as sigma

Author: iansan5653

code/corner_finding.py

@@ -105,9 +105,9 @@ def __init__(self,
 def find_corner_marks(image: np.ndarray) -> geometry_utils.Polygon:
     # Dilating helps find corner marks, but we don't want to mess up bubble fills
     # so it's only dilated after passing here
-    dilated_image = image_utils.dilate(image)
+    # dilated_image = image_utils.dilate(image)
     all_polygons: typing.List[
-        geometry_utils.Polygon] = image_utils.find_polygons(dilated_image)
+        geometry_utils.Polygon] = image_utils.find_polygons(image)
 
     # Even though the LMark and SquareMark classes check length, it's faster to
     # filter out the shapes of incorrect length despite the increased time

code/image_utils.py

@@ -1,5 +1,6 @@
 """Image filtering and processing utilities."""
 
+import math
 import pathlib
 import typing
 
@@ -18,7 +19,7 @@ def convert_to_grayscale(image: np.array) -> np.ndarray:
 
 def remove_hf_noise(image: np.array) -> np.ndarray:
     """Blur image slightly to remove high-frequency noise."""
-    return cv2.GaussianBlur(image, (3, 3), 0)
+    return cv2.GaussianBlur(image, (0, 0), sigmaX=math.sqrt(2))
 
 
 def detect_edges(image: np.array) -> np.ndarray: