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# pylint: skip-file
# -----------------------------------------------------------------------------------
# SCUNet: Practical Blind Denoising via Swin-Conv-UNet and Data Synthesis, https://arxiv.org/abs/2203.13278
# Zhang, Kai and Li, Yawei and Liang, Jingyun and Cao, Jiezhang and Zhang, Yulun and Tang, Hao and Timofte, Radu and Van Gool, Luc
# -----------------------------------------------------------------------------------
import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F
from einops import rearrange
from einops.layers.torch import Rearrange
from .timm.drop import DropPath
from .timm.weight_init import trunc_normal_
# Borrowed from https://github.com/cszn/SCUNet/blob/main/models/network_scunet.py
class WMSA(nn.Module):
"""Self-attention module in Swin Transformer"""
def __init__(self, input_dim, output_dim, head_dim, window_size, type):
super(WMSA, self).__init__()
self.input_dim = input_dim
self.output_dim = output_dim
self.head_dim = head_dim
self.scale = self.head_dim**-0.5
self.n_heads = input_dim // head_dim
self.window_size = window_size
self.type = type
self.embedding_layer = nn.Linear(self.input_dim, 3 * self.input_dim, bias=True)
self.relative_position_params = nn.Parameter(
torch.zeros((2 * window_size - 1) * (2 * window_size - 1), self.n_heads)
)
# TODO recover
# self.relative_position_params = nn.Parameter(torch.zeros(self.n_heads, 2 * window_size - 1, 2 * window_size -1))
self.relative_position_params = nn.Parameter(
torch.zeros((2 * window_size - 1) * (2 * window_size - 1), self.n_heads)
)
self.linear = nn.Linear(self.input_dim, self.output_dim)
trunc_normal_(self.relative_position_params, std=0.02)
self.relative_position_params = torch.nn.Parameter(
self.relative_position_params.view(
2 * window_size - 1, 2 * window_size - 1, self.n_heads
)
.transpose(1, 2)
.transpose(0, 1)
)
def generate_mask(self, h, w, p, shift):
"""generating the mask of SW-MSA
Args:
shift: shift parameters in CyclicShift.
Returns:
attn_mask: should be (1 1 w p p),
"""
# supporting square.
attn_mask = torch.zeros(
h,
w,
p,
p,
p,
p,
dtype=torch.bool,
device=self.relative_position_params.device,
)
if self.type == "W":
return attn_mask
s = p - shift
attn_mask[-1, :, :s, :, s:, :] = True
attn_mask[-1, :, s:, :, :s, :] = True
attn_mask[:, -1, :, :s, :, s:] = True
attn_mask[:, -1, :, s:, :, :s] = True
attn_mask = rearrange(
attn_mask, "w1 w2 p1 p2 p3 p4 -> 1 1 (w1 w2) (p1 p2) (p3 p4)"
)
return attn_mask
def forward(self, x):
"""Forward pass of Window Multi-head Self-attention module.
Args:
x: input tensor with shape of [b h w c];
attn_mask: attention mask, fill -inf where the value is True;
Returns:
output: tensor shape [b h w c]
"""
if self.type != "W":
x = torch.roll(
x,
shifts=(-(self.window_size // 2), -(self.window_size // 2)),
dims=(1, 2),
)
x = rearrange(
x,
"b (w1 p1) (w2 p2) c -> b w1 w2 p1 p2 c",
p1=self.window_size,
p2=self.window_size,
)
h_windows = x.size(1)
w_windows = x.size(2)
# square validation
# assert h_windows == w_windows
x = rearrange(
x,
"b w1 w2 p1 p2 c -> b (w1 w2) (p1 p2) c",
p1=self.window_size,
p2=self.window_size,
)
qkv = self.embedding_layer(x)
q, k, v = rearrange(
qkv, "b nw np (threeh c) -> threeh b nw np c", c=self.head_dim
).chunk(3, dim=0)
sim = torch.einsum("hbwpc,hbwqc->hbwpq", q, k) * self.scale
# Adding learnable relative embedding
sim = sim + rearrange(self.relative_embedding(), "h p q -> h 1 1 p q")
# Using Attn Mask to distinguish different subwindows.
if self.type != "W":
attn_mask = self.generate_mask(
h_windows, w_windows, self.window_size, shift=self.window_size // 2
)
sim = sim.masked_fill_(attn_mask, float("-inf"))
probs = nn.functional.softmax(sim, dim=-1)
output = torch.einsum("hbwij,hbwjc->hbwic", probs, v)
output = rearrange(output, "h b w p c -> b w p (h c)")
output = self.linear(output)
output = rearrange(
output,
"b (w1 w2) (p1 p2) c -> b (w1 p1) (w2 p2) c",
w1=h_windows,
p1=self.window_size,
)
if self.type != "W":
output = torch.roll(
output,
shifts=(self.window_size // 2, self.window_size // 2),
dims=(1, 2),
)
return output
def relative_embedding(self):
cord = torch.tensor(
np.array(
[
[i, j]
for i in range(self.window_size)
for j in range(self.window_size)
]
)
)
relation = cord[:, None, :] - cord[None, :, :] + self.window_size - 1
# negative is allowed
return self.relative_position_params[
:, relation[:, :, 0].long(), relation[:, :, 1].long()
]
class Block(nn.Module):
def __init__(
self,
input_dim,
output_dim,
head_dim,
window_size,
drop_path,
type="W",
input_resolution=None,
):
"""SwinTransformer Block"""
super(Block, self).__init__()
self.input_dim = input_dim
self.output_dim = output_dim
assert type in ["W", "SW"]
self.type = type
if input_resolution <= window_size:
self.type = "W"
self.ln1 = nn.LayerNorm(input_dim)
self.msa = WMSA(input_dim, input_dim, head_dim, window_size, self.type)
self.drop_path = DropPath(drop_path) if drop_path > 0.0 else nn.Identity()
self.ln2 = nn.LayerNorm(input_dim)
self.mlp = nn.Sequential(
nn.Linear(input_dim, 4 * input_dim),
nn.GELU(),
nn.Linear(4 * input_dim, output_dim),
)
def forward(self, x):
x = x + self.drop_path(self.msa(self.ln1(x)))
x = x + self.drop_path(self.mlp(self.ln2(x)))
return x
class ConvTransBlock(nn.Module):
def __init__(
self,
conv_dim,
trans_dim,
head_dim,
window_size,
drop_path,
type="W",
input_resolution=None,
):
"""SwinTransformer and Conv Block"""
super(ConvTransBlock, self).__init__()
self.conv_dim = conv_dim
self.trans_dim = trans_dim
self.head_dim = head_dim
self.window_size = window_size
self.drop_path = drop_path
self.type = type
self.input_resolution = input_resolution
assert self.type in ["W", "SW"]
if self.input_resolution <= self.window_size:
self.type = "W"
self.trans_block = Block(
self.trans_dim,
self.trans_dim,
self.head_dim,
self.window_size,
self.drop_path,
self.type,
self.input_resolution,
)
self.conv1_1 = nn.Conv2d(
self.conv_dim + self.trans_dim,
self.conv_dim + self.trans_dim,
1,
1,
0,
bias=True,
)
self.conv1_2 = nn.Conv2d(
self.conv_dim + self.trans_dim,
self.conv_dim + self.trans_dim,
1,
1,
0,
bias=True,
)
self.conv_block = nn.Sequential(
nn.Conv2d(self.conv_dim, self.conv_dim, 3, 1, 1, bias=False),
nn.ReLU(True),
nn.Conv2d(self.conv_dim, self.conv_dim, 3, 1, 1, bias=False),
)
def forward(self, x):
conv_x, trans_x = torch.split(
self.conv1_1(x), (self.conv_dim, self.trans_dim), dim=1
)
conv_x = self.conv_block(conv_x) + conv_x
trans_x = Rearrange("b c h w -> b h w c")(trans_x)
trans_x = self.trans_block(trans_x)
trans_x = Rearrange("b h w c -> b c h w")(trans_x)
res = self.conv1_2(torch.cat((conv_x, trans_x), dim=1))
x = x + res
return x
class SCUNet(nn.Module):
def __init__(
self,
state_dict,
in_nc=3,
config=[4, 4, 4, 4, 4, 4, 4],
dim=64,
drop_path_rate=0.0,
input_resolution=256,
):
super(SCUNet, self).__init__()
self.model_arch = "SCUNet"
self.sub_type = "SR"
self.num_filters: int = 0
self.state = state_dict
self.config = config
self.dim = dim
self.head_dim = 32
self.window_size = 8
self.in_nc = in_nc
self.out_nc = self.in_nc
self.scale = 1
self.supports_fp16 = True
# drop path rate for each layer
dpr = [x.item() for x in torch.linspace(0, drop_path_rate, sum(config))]
self.m_head = [nn.Conv2d(in_nc, dim, 3, 1, 1, bias=False)]
begin = 0
self.m_down1 = [
ConvTransBlock(
dim // 2,
dim // 2,
self.head_dim,
self.window_size,
dpr[i + begin],
"W" if not i % 2 else "SW",
input_resolution,
)
for i in range(config[0])
] + [nn.Conv2d(dim, 2 * dim, 2, 2, 0, bias=False)]
begin += config[0]
self.m_down2 = [
ConvTransBlock(
dim,
dim,
self.head_dim,
self.window_size,
dpr[i + begin],
"W" if not i % 2 else "SW",
input_resolution // 2,
)
for i in range(config[1])
] + [nn.Conv2d(2 * dim, 4 * dim, 2, 2, 0, bias=False)]
begin += config[1]
self.m_down3 = [
ConvTransBlock(
2 * dim,
2 * dim,
self.head_dim,
self.window_size,
dpr[i + begin],
"W" if not i % 2 else "SW",
input_resolution // 4,
)
for i in range(config[2])
] + [nn.Conv2d(4 * dim, 8 * dim, 2, 2, 0, bias=False)]
begin += config[2]
self.m_body = [
ConvTransBlock(
4 * dim,
4 * dim,
self.head_dim,
self.window_size,
dpr[i + begin],
"W" if not i % 2 else "SW",
input_resolution // 8,
)
for i in range(config[3])
]
begin += config[3]
self.m_up3 = [
nn.ConvTranspose2d(8 * dim, 4 * dim, 2, 2, 0, bias=False),
] + [
ConvTransBlock(
2 * dim,
2 * dim,
self.head_dim,
self.window_size,
dpr[i + begin],
"W" if not i % 2 else "SW",
input_resolution // 4,
)
for i in range(config[4])
]
begin += config[4]
self.m_up2 = [
nn.ConvTranspose2d(4 * dim, 2 * dim, 2, 2, 0, bias=False),
] + [
ConvTransBlock(
dim,
dim,
self.head_dim,
self.window_size,
dpr[i + begin],
"W" if not i % 2 else "SW",
input_resolution // 2,
)
for i in range(config[5])
]
begin += config[5]
self.m_up1 = [
nn.ConvTranspose2d(2 * dim, dim, 2, 2, 0, bias=False),
] + [
ConvTransBlock(
dim // 2,
dim // 2,
self.head_dim,
self.window_size,
dpr[i + begin],
"W" if not i % 2 else "SW",
input_resolution,
)
for i in range(config[6])
]
self.m_tail = [nn.Conv2d(dim, in_nc, 3, 1, 1, bias=False)]
self.m_head = nn.Sequential(*self.m_head)
self.m_down1 = nn.Sequential(*self.m_down1)
self.m_down2 = nn.Sequential(*self.m_down2)
self.m_down3 = nn.Sequential(*self.m_down3)
self.m_body = nn.Sequential(*self.m_body)
self.m_up3 = nn.Sequential(*self.m_up3)
self.m_up2 = nn.Sequential(*self.m_up2)
self.m_up1 = nn.Sequential(*self.m_up1)
self.m_tail = nn.Sequential(*self.m_tail)
# self.apply(self._init_weights)
self.load_state_dict(state_dict, strict=True)
def check_image_size(self, x):
_, _, h, w = x.size()
mod_pad_h = (64 - h % 64) % 64
mod_pad_w = (64 - w % 64) % 64
x = F.pad(x, (0, mod_pad_w, 0, mod_pad_h), "reflect")
return x
def forward(self, x0):
h, w = x0.size()[-2:]
x0 = self.check_image_size(x0)
x1 = self.m_head(x0)
x2 = self.m_down1(x1)
x3 = self.m_down2(x2)
x4 = self.m_down3(x3)
x = self.m_body(x4)
x = self.m_up3(x + x4)
x = self.m_up2(x + x3)
x = self.m_up1(x + x2)
x = self.m_tail(x + x1)
x = x[:, :, :h, :w]
return x
def _init_weights(self, m):
if isinstance(m, nn.Linear):
trunc_normal_(m.weight, std=0.02)
if m.bias is not None:
nn.init.constant_(m.bias, 0)
elif isinstance(m, nn.LayerNorm):
nn.init.constant_(m.bias, 0)
nn.init.constant_(m.weight, 1.0)
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