# modify from https://github.com/rosinality/stylegan2-pytorch/blob/master/op/upfirdn2d.py # noqa:E501
import os
import torch
from torch.autograd import Function
from torch.nn import functional as F
BASICSR_JIT = os.getenv('BASICSR_JIT')
if BASICSR_JIT == 'True':
from torch.utils.cpp_extension import load
module_path = os.path.dirname(__file__)
upfirdn2d_ext = load(
'upfirdn2d',
sources=[
os.path.join(module_path, 'src', 'upfirdn2d.cpp'),
os.path.join(module_path, 'src', 'upfirdn2d_kernel.cu'),
],
)
else:
try:
from . import upfirdn2d_ext
except ImportError:
pass
# avoid annoying print output
# print(f'Cannot import deform_conv_ext. Error: {error}. You may need to: \n '
# '1. compile with BASICSR_EXT=True. or\n '
# '2. set BASICSR_JIT=True during running')
[docs]class UpFirDn2dBackward(Function):
[docs] @staticmethod
def forward(ctx, grad_output, kernel, grad_kernel, up, down, pad, g_pad, in_size, out_size):
up_x, up_y = up
down_x, down_y = down
g_pad_x0, g_pad_x1, g_pad_y0, g_pad_y1 = g_pad
grad_output = grad_output.reshape(-1, out_size[0], out_size[1], 1)
grad_input = upfirdn2d_ext.upfirdn2d(
grad_output,
grad_kernel,
down_x,
down_y,
up_x,
up_y,
g_pad_x0,
g_pad_x1,
g_pad_y0,
g_pad_y1,
)
grad_input = grad_input.view(in_size[0], in_size[1], in_size[2], in_size[3])
ctx.save_for_backward(kernel)
pad_x0, pad_x1, pad_y0, pad_y1 = pad
ctx.up_x = up_x
ctx.up_y = up_y
ctx.down_x = down_x
ctx.down_y = down_y
ctx.pad_x0 = pad_x0
ctx.pad_x1 = pad_x1
ctx.pad_y0 = pad_y0
ctx.pad_y1 = pad_y1
ctx.in_size = in_size
ctx.out_size = out_size
return grad_input
[docs] @staticmethod
def backward(ctx, gradgrad_input):
kernel, = ctx.saved_tensors
gradgrad_input = gradgrad_input.reshape(-1, ctx.in_size[2], ctx.in_size[3], 1)
gradgrad_out = upfirdn2d_ext.upfirdn2d(
gradgrad_input,
kernel,
ctx.up_x,
ctx.up_y,
ctx.down_x,
ctx.down_y,
ctx.pad_x0,
ctx.pad_x1,
ctx.pad_y0,
ctx.pad_y1,
)
# gradgrad_out = gradgrad_out.view(ctx.in_size[0], ctx.out_size[0],
# ctx.out_size[1], ctx.in_size[3])
gradgrad_out = gradgrad_out.view(ctx.in_size[0], ctx.in_size[1], ctx.out_size[0], ctx.out_size[1])
return gradgrad_out, None, None, None, None, None, None, None, None
[docs]class UpFirDn2d(Function):
[docs] @staticmethod
def forward(ctx, input, kernel, up, down, pad):
up_x, up_y = up
down_x, down_y = down
pad_x0, pad_x1, pad_y0, pad_y1 = pad
kernel_h, kernel_w = kernel.shape
_, channel, in_h, in_w = input.shape
ctx.in_size = input.shape
input = input.reshape(-1, in_h, in_w, 1)
ctx.save_for_backward(kernel, torch.flip(kernel, [0, 1]))
out_h = (in_h * up_y + pad_y0 + pad_y1 - kernel_h) // down_y + 1
out_w = (in_w * up_x + pad_x0 + pad_x1 - kernel_w) // down_x + 1
ctx.out_size = (out_h, out_w)
ctx.up = (up_x, up_y)
ctx.down = (down_x, down_y)
ctx.pad = (pad_x0, pad_x1, pad_y0, pad_y1)
g_pad_x0 = kernel_w - pad_x0 - 1
g_pad_y0 = kernel_h - pad_y0 - 1
g_pad_x1 = in_w * up_x - out_w * down_x + pad_x0 - up_x + 1
g_pad_y1 = in_h * up_y - out_h * down_y + pad_y0 - up_y + 1
ctx.g_pad = (g_pad_x0, g_pad_x1, g_pad_y0, g_pad_y1)
out = upfirdn2d_ext.upfirdn2d(input, kernel, up_x, up_y, down_x, down_y, pad_x0, pad_x1, pad_y0, pad_y1)
# out = out.view(major, out_h, out_w, minor)
out = out.view(-1, channel, out_h, out_w)
return out
[docs] @staticmethod
def backward(ctx, grad_output):
kernel, grad_kernel = ctx.saved_tensors
grad_input = UpFirDn2dBackward.apply(
grad_output,
kernel,
grad_kernel,
ctx.up,
ctx.down,
ctx.pad,
ctx.g_pad,
ctx.in_size,
ctx.out_size,
)
return grad_input, None, None, None, None
[docs]def upfirdn2d(input, kernel, up=1, down=1, pad=(0, 0)):
if input.device.type == 'cpu':
out = upfirdn2d_native(input, kernel, up, up, down, down, pad[0], pad[1], pad[0], pad[1])
else:
out = UpFirDn2d.apply(input, kernel, (up, up), (down, down), (pad[0], pad[1], pad[0], pad[1]))
return out
[docs]def upfirdn2d_native(input, kernel, up_x, up_y, down_x, down_y, pad_x0, pad_x1, pad_y0, pad_y1):
_, channel, in_h, in_w = input.shape
input = input.reshape(-1, in_h, in_w, 1)
_, in_h, in_w, minor = input.shape
kernel_h, kernel_w = kernel.shape
out = input.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 + 1
out_w = (in_w * up_x + pad_x0 + pad_x1 - kernel_w) // down_x + 1
return out.view(-1, channel, out_h, out_w)