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import hashlib
import os
import requests
import torch
import torch.nn as nn
from tqdm import tqdm
URL_MAP = {"vgg_lpips": "https://heibox.uni-heidelberg.de/f/607503859c864bc1b30b/?dl=1"}
CKPT_MAP = {"vgg_lpips": "vgg.pth"}
MD5_MAP = {"vgg_lpips": "d507d7349b931f0638a25a48a722f98a"}
def download(url, local_path, chunk_size=1024):
os.makedirs(os.path.split(local_path)[0], exist_ok=True)
with requests.get(url, stream=True) as r:
total_size = int(r.headers.get("content-length", 0))
with tqdm(total=total_size, unit="B", unit_scale=True) as pbar:
with open(local_path, "wb") as f:
for data in r.iter_content(chunk_size=chunk_size):
if data:
f.write(data)
pbar.update(chunk_size)
def md5_hash(path):
with open(path, "rb") as f:
content = f.read()
return hashlib.md5(content).hexdigest()
def get_ckpt_path(name, root, check=False):
assert name in URL_MAP
path = os.path.join(root, CKPT_MAP[name])
if not os.path.exists(path) or (check and not md5_hash(path) == MD5_MAP[name]):
print("Downloading {} model from {} to {}".format(name, URL_MAP[name], path))
download(URL_MAP[name], path)
md5 = md5_hash(path)
assert md5 == MD5_MAP[name], md5
return path
class ActNorm(nn.Module):
def __init__(
self, num_features, logdet=False, affine=True, allow_reverse_init=False
):
assert affine
super().__init__()
self.logdet = logdet
self.loc = nn.Parameter(torch.zeros(1, num_features, 1, 1))
self.scale = nn.Parameter(torch.ones(1, num_features, 1, 1))
self.allow_reverse_init = allow_reverse_init
self.register_buffer("initialized", torch.tensor(0, dtype=torch.uint8))
def initialize(self, input):
with torch.no_grad():
flatten = input.permute(1, 0, 2, 3).contiguous().view(input.shape[1], -1)
mean = (
flatten.mean(1)
.unsqueeze(1)
.unsqueeze(2)
.unsqueeze(3)
.permute(1, 0, 2, 3)
)
std = (
flatten.std(1)
.unsqueeze(1)
.unsqueeze(2)
.unsqueeze(3)
.permute(1, 0, 2, 3)
)
self.loc.data.copy_(-mean)
self.scale.data.copy_(1 / (std + 1e-6))
def forward(self, input, reverse=False):
if reverse:
return self.reverse(input)
if len(input.shape) == 2:
input = input[:, :, None, None]
squeeze = True
else:
squeeze = False
_, _, height, width = input.shape
if self.training and self.initialized.item() == 0:
self.initialize(input)
self.initialized.fill_(1)
h = self.scale * (input + self.loc)
if squeeze:
h = h.squeeze(-1).squeeze(-1)
if self.logdet:
log_abs = torch.log(torch.abs(self.scale))
logdet = height * width * torch.sum(log_abs)
logdet = logdet * torch.ones(input.shape[0]).to(input)
return h, logdet
return h
def reverse(self, output):
if self.training and self.initialized.item() == 0:
if not self.allow_reverse_init:
raise RuntimeError(
"Initializing ActNorm in reverse direction is "
"disabled by default. Use allow_reverse_init=True to enable."
)
else:
self.initialize(output)
self.initialized.fill_(1)
if len(output.shape) == 2:
output = output[:, :, None, None]
squeeze = True
else:
squeeze = False
h = output / self.scale - self.loc
if squeeze:
h = h.squeeze(-1).squeeze(-1)
return h
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