Create stylegan_op_upfirdn2d.py

stylegan_op_upfirdn2d.py

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+from collections import abc
+
+import torch
+from torch.nn import functional as F
+
+
+def upfirdn2d(inputs, kernel, up=1, down=1, pad=(0, 0)):
+    if not isinstance(up, abc.Iterable):
+        up = (up, up)
+
+    if not isinstance(down, abc.Iterable):
+        down = (down, down)
+
+    if len(pad) == 2:
+        pad = (pad[0], pad[1], pad[0], pad[1])
+
+    return upfirdn2d_native(inputs, kernel, *up, *down, *pad)
+
+
+def upfirdn2d_native(
+    inputs, kernel, up_x, up_y, down_x, down_y, pad_x0, pad_x1, pad_y0, pad_y1
+):
+    _, channel, in_h, in_w = inputs.shape
+    inputs = inputs.reshape(-1, in_h, in_w, 1)
+
+    _, in_h, in_w, minor = inputs.shape
+    kernel_h, kernel_w = kernel.shape
+
+    out = inputs.view(-1, in_h, 1, in_w, 1, minor)
+    out = F.pad(out, [0, 0, 0, up_x - 1, 0, 0, 0, up_y - 1])
+    out = out.view(-1, in_h * up_y, in_w * up_x, minor)
+
+    out = F.pad(
+        out, [0, 0, max(pad_x0, 0), max(pad_x1, 0), max(pad_y0, 0), max(pad_y1, 0)]
+    )
+    out = out[
+          :,
+          max(-pad_y0, 0): out.shape[1] - max(-pad_y1, 0),
+          max(-pad_x0, 0): out.shape[2] - max(-pad_x1, 0),
+          :,
+          ]
+
+    out = out.permute(0, 3, 1, 2)
+    out = out.reshape(
+        [-1, 1, in_h * up_y + pad_y0 + pad_y1, in_w * up_x + pad_x0 + pad_x1]
+    )
+    w = torch.flip(kernel, [0, 1]).view(1, 1, kernel_h, kernel_w)
+    out = F.conv2d(out, w)
+    out = out.reshape(
+        -1,
+        minor,
+        in_h * up_y + pad_y0 + pad_y1 - kernel_h + 1,
+        in_w * up_x + pad_x0 + pad_x1 - kernel_w + 1,
+    )
+    out = out.permute(0, 2, 3, 1)
+    out = out[:, ::down_y, ::down_x, :]
+
+    out_h = (in_h * up_y + pad_y0 + pad_y1 - kernel_h + down_y) // down_y
+    out_w = (in_w * up_x + pad_x0 + pad_x1 - kernel_w + down_x) // down_x
+
+    return out.view(-1, channel, out_h, out_w)