Change gaussian kernel to anisotropic kernel. (#199)

Change gaussian kernel to anisotropic kernel. (#199)

modules/anisotropic.py

@@ -0,0 +1,185 @@
+import torch
+
+
+Tensor = torch.Tensor
+Device = torch.DeviceObjType
+Dtype = torch.Type
+pad = torch.nn.functional.pad
+
+
+def _compute_zero_padding(kernel_size: tuple[int, int] | int) -> tuple[int, int]:
+    ky, kx = _unpack_2d_ks(kernel_size)
+    return (ky - 1) // 2, (kx - 1) // 2
+
+
+def _unpack_2d_ks(kernel_size: tuple[int, int] | int) -> tuple[int, int]:
+    if isinstance(kernel_size, int):
+        ky = kx = kernel_size
+    else:
+        assert len(kernel_size) == 2, '2D Kernel size should have a length of 2.'
+        ky, kx = kernel_size
+
+    ky = int(ky)
+    kx = int(kx)
+    return ky, kx
+
+
+def gaussian(
+    window_size: int, sigma: Tensor | float, *, device: Device | None = None, dtype: Dtype | None = None
+) -> Tensor:
+
+    batch_size = sigma.shape[0]
+
+    x = (torch.arange(window_size, device=sigma.device, dtype=sigma.dtype) - window_size // 2).expand(batch_size, -1)
+
+    if window_size % 2 == 0:
+        x = x + 0.5
+
+    gauss = torch.exp(-x.pow(2.0) / (2 * sigma.pow(2.0)))
+
+    return gauss / gauss.sum(-1, keepdim=True)
+
+
+def get_gaussian_kernel1d(
+    kernel_size: int,
+    sigma: float | Tensor,
+    force_even: bool = False,
+    *,
+    device: Device | None = None,
+    dtype: Dtype | None = None,
+) -> Tensor:
+
+    return gaussian(kernel_size, sigma, device=device, dtype=dtype)
+
+
+def get_gaussian_kernel2d(
+    kernel_size: tuple[int, int] | int,
+    sigma: tuple[float, float] | Tensor,
+    force_even: bool = False,
+    *,
+    device: Device | None = None,
+    dtype: Dtype | None = None,
+) -> Tensor:
+
+    sigma = torch.Tensor([[sigma, sigma]]).to(device=device, dtype=dtype)
+
+    ksize_y, ksize_x = _unpack_2d_ks(kernel_size)
+    sigma_y, sigma_x = sigma[:, 0, None], sigma[:, 1, None]
+
+    kernel_y = get_gaussian_kernel1d(ksize_y, sigma_y, force_even, device=device, dtype=dtype)[..., None]
+    kernel_x = get_gaussian_kernel1d(ksize_x, sigma_x, force_even, device=device, dtype=dtype)[..., None]
+
+    return kernel_y * kernel_x.view(-1, 1, ksize_x)
+
+
+def _bilateral_blur(
+    input: Tensor,
+    guidance: Tensor | None,
+    kernel_size: tuple[int, int] | int,
+    sigma_color: float | Tensor,
+    sigma_space: tuple[float, float] | Tensor,
+    border_type: str = 'reflect',
+    color_distance_type: str = 'l1',
+) -> Tensor:
+
+    if isinstance(sigma_color, Tensor):
+        sigma_color = sigma_color.to(device=input.device, dtype=input.dtype).view(-1, 1, 1, 1, 1)
+
+    ky, kx = _unpack_2d_ks(kernel_size)
+    pad_y, pad_x = _compute_zero_padding(kernel_size)
+
+    padded_input = pad(input, (pad_x, pad_x, pad_y, pad_y), mode=border_type)
+    unfolded_input = padded_input.unfold(2, ky, 1).unfold(3, kx, 1).flatten(-2)  # (B, C, H, W, Ky x Kx)
+
+    if guidance is None:
+        guidance = input
+        unfolded_guidance = unfolded_input
+    else:
+        padded_guidance = pad(guidance, (pad_x, pad_x, pad_y, pad_y), mode=border_type)
+        unfolded_guidance = padded_guidance.unfold(2, ky, 1).unfold(3, kx, 1).flatten(-2)  # (B, C, H, W, Ky x Kx)
+
+    diff = unfolded_guidance - guidance.unsqueeze(-1)
+    if color_distance_type == "l1":
+        color_distance_sq = diff.abs().sum(1, keepdim=True).square()
+    elif color_distance_type == "l2":
+        color_distance_sq = diff.square().sum(1, keepdim=True)
+    else:
+        raise ValueError("color_distance_type only acceps l1 or l2")
+    color_kernel = (-0.5 / sigma_color**2 * color_distance_sq).exp()  # (B, 1, H, W, Ky x Kx)
+
+    space_kernel = get_gaussian_kernel2d(kernel_size, sigma_space, device=input.device, dtype=input.dtype)
+    space_kernel = space_kernel.view(-1, 1, 1, 1, kx * ky)
+
+    kernel = space_kernel * color_kernel
+    out = (unfolded_input * kernel).sum(-1) / kernel.sum(-1)
+    return out
+
+
+def bilateral_blur(
+    input: Tensor,
+    kernel_size: tuple[int, int] | int = (13, 13),
+    sigma_color: float | Tensor = 3.0,
+    sigma_space: tuple[float, float] | Tensor = 3.0,
+    border_type: str = 'reflect',
+    color_distance_type: str = 'l1',
+) -> Tensor:
+    return _bilateral_blur(input, None, kernel_size, sigma_color, sigma_space, border_type, color_distance_type)
+
+
+def joint_bilateral_blur(
+    input: Tensor,
+    guidance: Tensor,
+    kernel_size: tuple[int, int] | int,
+    sigma_color: float | Tensor,
+    sigma_space: tuple[float, float] | Tensor,
+    border_type: str = 'reflect',
+    color_distance_type: str = 'l1',
+) -> Tensor:
+    return _bilateral_blur(input, guidance, kernel_size, sigma_color, sigma_space, border_type, color_distance_type)
+
+
+class _BilateralBlur(torch.nn.Module):
+    def __init__(
+        self,
+        kernel_size: tuple[int, int] | int,
+        sigma_color: float | Tensor,
+        sigma_space: tuple[float, float] | Tensor,
+        border_type: str = 'reflect',
+        color_distance_type: str = "l1",
+    ) -> None:
+        super().__init__()
+        self.kernel_size = kernel_size
+        self.sigma_color = sigma_color
+        self.sigma_space = sigma_space
+        self.border_type = border_type
+        self.color_distance_type = color_distance_type
+
+    def __repr__(self) -> str:
+        return (
+            f"{self.__class__.__name__}"
+            f"(kernel_size={self.kernel_size}, "
+            f"sigma_color={self.sigma_color}, "
+            f"sigma_space={self.sigma_space}, "
+            f"border_type={self.border_type}, "
+            f"color_distance_type={self.color_distance_type})"
+        )
+
+
+class BilateralBlur(_BilateralBlur):
+    def forward(self, input: Tensor) -> Tensor:
+        return bilateral_blur(
+            input, self.kernel_size, self.sigma_color, self.sigma_space, self.border_type, self.color_distance_type
+        )
+
+
+class JointBilateralBlur(_BilateralBlur):
+    def forward(self, input: Tensor, guidance: Tensor) -> Tensor:
+        return joint_bilateral_blur(
+            input,
+            guidance,
+            self.kernel_size,
+            self.sigma_color,
+            self.sigma_space,
+            self.border_type,
+            self.color_distance_type,
+        )