Clear optical distortion (#2176)

* Empty-Commit

* Cleanup in Optical Distortion

* Fixed fisheye

albumentations/augmentations/geometric/functional.py

@@ -3356,26 +3356,23 @@ def tps_transform(
 
 def get_camera_matrix_distortion_maps(
     image_shape: tuple[int, int],
-    cx: float,
-    cy: float,
     k: float,
+    center_xy: tuple[float, float],
 ) -> tuple[np.ndarray, np.ndarray]:
     """Generate distortion maps using camera matrix model.
 
     Args:
         image_shape: Image shape
-        cx: x-coordinate of distortion center
-        cy: y-coordinate of distortion center
         k: Distortion coefficient
-
+        center_xy: Center of distortion
     Returns:
         tuple of:
         - map_x: Horizontal displacement map
         - map_y: Vertical displacement map
     """
     height, width = image_shape[:2]
     camera_matrix = np.array(
-        [[width, 0, cx], [0, height, cy], [0, 0, 1]],
+        [[width, 0, center_xy[0]], [0, height, center_xy[1]], [0, 0, 1]],
         dtype=np.float32,
     )
     distortion = np.array([k, k, 0, 0, 0], dtype=np.float32)
@@ -3391,38 +3388,43 @@ def get_camera_matrix_distortion_maps(
 
 def get_fisheye_distortion_maps(
     image_shape: tuple[int, int],
-    cx: float,
-    cy: float,
     k: float,
+    center_xy: tuple[float, float],
 ) -> tuple[np.ndarray, np.ndarray]:
     """Generate distortion maps using fisheye model.
 
     Args:
         image_shape: Image shape
-        cx: x-coordinate of distortion center
-        cy: y-coordinate of distortion center
         k: Distortion coefficient
-
+        center_xy: Center of distortion
     Returns:
         tuple of:
         - map_x: Horizontal displacement map
         - map_y: Vertical displacement map
     """
     height, width = image_shape[:2]
+
+    center_x, center_y = center_xy
+
     # Create coordinate grid
     y, x = np.mgrid[:height, :width].astype(np.float32)
-    x = x - cx
-    y = y - cy
+
+    x = x - center_x
+    y = y - center_y
 
     # Calculate polar coordinates
     r = np.sqrt(x * x + y * y)
     theta = np.arctan2(y, x)
 
-    # Apply fisheye distortion
-    r_dist = r * (1 + k * r * r)
+    # Normalize radius by the maximum possible radius to keep distortion in check
+    max_radius = math.sqrt(max(center_x, width - center_x) ** 2 + max(center_y, height - center_y) ** 2)
+    r_norm = r / max_radius
+
+    # Apply fisheye distortion to normalized radius
+    r_dist = r * (1 + k * r_norm * r_norm)
 
     # Convert back to cartesian coordinates
-    map_x = cx + r_dist * np.cos(theta)
-    map_y = cy + r_dist * np.sin(theta)
+    map_x = r_dist * np.cos(theta) + center_x
+    map_y = r_dist * np.sin(theta) + center_y
 
     return map_x, map_y

albumentations/augmentations/geometric/transforms.py

@@ -1532,13 +1532,6 @@ class OpticalDistortion(BaseDistortion):
             For fisheye model: recommended range (-0.3, 0.3)
             Default: (-0.05, 0.05)
 
-        shift_limit (float | tuple[float, float]): Range of relative shifts for the image center.
-            Values are multiplied by image dimensions to get absolute shift in pixels:
-            - dx = shift_x * image_width
-            - dy = shift_y * image_height
-            If shift_limit is a single float value, the range will be (-shift_limit, shift_limit).
-            Default: (-0.05, 0.05)
-
         mode (Literal['camera', 'fisheye']): Distortion model to use:
             - 'camera': Original camera matrix model
             - 'fisheye': Fisheye lens model
@@ -1571,7 +1564,7 @@ class OpticalDistortion(BaseDistortion):
     Example:
         >>> import albumentations as A
         >>> transform = A.Compose([
-        ...     A.OpticalDistortion(distort_limit=0.1, shift_limit=0.1, p=1.0),
+        ...     A.OpticalDistortion(distort_limit=0.1, p=1.0),
         ... ])
         >>> transformed = transform(image=image, mask=mask, bboxes=bboxes, keypoints=keypoints)
         >>> transformed_image = transformed['image']
@@ -1582,8 +1575,10 @@ class OpticalDistortion(BaseDistortion):
 
     class InitSchema(BaseDistortion.InitSchema):
         distort_limit: SymmetricRangeType
-        shift_limit: SymmetricRangeType
         mode: Literal["camera", "fisheye"]
+        shift_limit: SymmetricRangeType | None = Field(
+            deprecated="Deprecated. Does not have any effect.",
+        )
         value: ColorType | None = Field(
             deprecated="Deprecated. Does not have any effect.",
         )
@@ -1597,7 +1592,7 @@ class InitSchema(BaseDistortion.InitSchema):
     def __init__(
         self,
         distort_limit: ScaleFloatType = (-0.05, 0.05),
-        shift_limit: ScaleFloatType = (-0.05, 0.05),
+        shift_limit: ScaleFloatType | None = None,
         interpolation: int = cv2.INTER_LINEAR,
         border_mode: int | None = None,
         value: ColorType | None = None,
@@ -1612,7 +1607,6 @@ def __init__(
             mask_interpolation=mask_interpolation,
             p=p,
         )
-        self.shift_limit = cast(tuple[float, float], shift_limit)
         self.distort_limit = cast(tuple[float, float], distort_limit)
         self.mode = mode
 
@@ -1628,33 +1622,27 @@ def get_params_dependent_on_data(
         k = self.py_random.uniform(*self.distort_limit)
 
         # Calculate center shift
-        dx = round(self.py_random.uniform(*self.shift_limit) * width)
-        dy = round(self.py_random.uniform(*self.shift_limit) * height)
-        cx = width * 0.5 + dx
-        cy = height * 0.5 + dy
+        center_xy = fgeometric.center(image_shape)
 
         # Get distortion maps based on mode
         if self.mode == "camera":
             map_x, map_y = fgeometric.get_camera_matrix_distortion_maps(
                 image_shape,
-                cx,
-                cy,
                 k,
+                center_xy,
             )
         else:  # fisheye
             map_x, map_y = fgeometric.get_fisheye_distortion_maps(
                 image_shape,
-                cx,
-                cy,
                 k,
+                center_xy,
             )
 
         return {"map_x": map_x, "map_y": map_y}
 
     def get_transform_init_args_names(self) -> tuple[str, ...]:
         return (
             "distort_limit",
-            "shift_limit",
             "mode",
             *super().get_transform_init_args_names(),
         )

tests/aug_definitions.py

@@ -133,8 +133,7 @@
         A.OpticalDistortion,
         {
             "distort_limit": 0.2,
-            "shift_limit": 0.2,
-            "interpolation": cv2.INTER_CUBIC,
+            "interpolation": cv2.INTER_AREA,
         },
     ],
     [

tests/files/transform_serialization_v2_with_totensor.json

@@ -233,10 +233,6 @@
                     -0.05,
                     0.05
                 ],
-                "shift_limit": [
-                    -0.05,
-                    0.05
-                ],
                 "interpolation": 1,
                 "mode": "camera"
             },

tests/files/transform_serialization_v2_without_totensor.json

@@ -235,10 +235,6 @@
                     -0.05,
                     0.05
                 ],
-                "shift_limit": [
-                    -0.05,
-                    0.05
-                ],
                 "interpolation": 1,
                 "mode": "camera"
             },

tests/files/transform_v1.1.0_with_totensor.json

@@ -227,10 +227,6 @@
                     -0.05,
                     0.05
                 ],
-                "shift_limit": [
-                    -0.05,
-                    0.05
-                ],
                 "interpolation": 1,
                 "mode": "camera"
             },

tests/files/transform_v1.1.0_without_totensor.json

@@ -227,10 +227,6 @@
                     -0.05,
                     0.05
                 ],
-                "shift_limit": [
-                    -0.05,
-                    0.05
-                ],
                 "interpolation": 1,
                 "mode": "camera"
             },