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# Modified from:
# taming-transformers: https://github.com/CompVis/taming-transformers
# muse-maskgit-pytorch: https://github.com/lucidrains/muse-maskgit-pytorch/blob/main/muse_maskgit_pytorch/vqgan_vae.py
import torch
import torch.nn as nn
import torch.nn.functional as F
from tokenizer.tokenizer_image.lpips import LPIPS
from tokenizer.tokenizer_image.discriminator_patchgan import NLayerDiscriminator as PatchGANDiscriminator
from tokenizer.tokenizer_image.discriminator_stylegan import Discriminator as StyleGANDiscriminator
def hinge_d_loss(logits_real, logits_fake):
loss_real = torch.mean(F.relu(1. - logits_real))
loss_fake = torch.mean(F.relu(1. + logits_fake))
d_loss = 0.5 * (loss_real + loss_fake)
return d_loss
def vanilla_d_loss(logits_real, logits_fake):
loss_real = torch.mean(F.softplus(-logits_real))
loss_fake = torch.mean(F.softplus(logits_fake))
d_loss = 0.5 * (loss_real + loss_fake)
return d_loss
def non_saturating_d_loss(logits_real, logits_fake):
loss_real = torch.mean(F.binary_cross_entropy_with_logits(torch.ones_like(logits_real), logits_real))
loss_fake = torch.mean(F.binary_cross_entropy_with_logits(torch.zeros_like(logits_fake), logits_fake))
d_loss = 0.5 * (loss_real + loss_fake)
return d_loss
def hinge_gen_loss(logit_fake):
return -torch.mean(logit_fake)
def non_saturating_gen_loss(logit_fake):
return torch.mean(F.binary_cross_entropy_with_logits(torch.ones_like(logit_fake), logit_fake))
def adopt_weight(weight, global_step, threshold=0, value=0.):
if global_step < threshold:
weight = value
return weight
class VQLoss(nn.Module):
def __init__(self, disc_start, disc_loss="hinge", disc_dim=64, disc_type='patchgan', image_size=256,
disc_num_layers=3, disc_in_channels=3, disc_weight=1.0, disc_adaptive_weight = False,
gen_adv_loss='hinge', reconstruction_loss='l2', reconstruction_weight=1.0,
codebook_weight=1.0, perceptual_weight=1.0,
):
super().__init__()
# discriminator loss
assert disc_type in ["patchgan", "stylegan"]
assert disc_loss in ["hinge", "vanilla", "non-saturating"]
if disc_type == "patchgan":
self.discriminator = PatchGANDiscriminator(
input_nc=disc_in_channels,
n_layers=disc_num_layers,
ndf=disc_dim,
)
elif disc_type == "stylegan":
self.discriminator = StyleGANDiscriminator(
input_nc=disc_in_channels,
image_size=image_size,
)
else:
raise ValueError(f"Unknown GAN discriminator type '{disc_type}'.")
if disc_loss == "hinge":
self.disc_loss = hinge_d_loss
elif disc_loss == "vanilla":
self.disc_loss = vanilla_d_loss
elif disc_loss == "non-saturating":
self.disc_loss = non_saturating_d_loss
else:
raise ValueError(f"Unknown GAN discriminator loss '{disc_loss}'.")
self.discriminator_iter_start = disc_start
self.disc_weight = disc_weight
self.disc_adaptive_weight = disc_adaptive_weight
assert gen_adv_loss in ["hinge", "non-saturating"]
# gen_adv_loss
if gen_adv_loss == "hinge":
self.gen_adv_loss = hinge_gen_loss
elif gen_adv_loss == "non-saturating":
self.gen_adv_loss = non_saturating_gen_loss
else:
raise ValueError(f"Unknown GAN generator loss '{gen_adv_loss}'.")
# perceptual loss
self.perceptual_loss = LPIPS().eval()
self.perceptual_weight = perceptual_weight
# reconstruction loss
if reconstruction_loss == "l1":
self.rec_loss = F.l1_loss
elif reconstruction_loss == "l2":
self.rec_loss = F.mse_loss
else:
raise ValueError(f"Unknown rec loss '{reconstruction_loss}'.")
self.rec_weight = reconstruction_weight
# codebook loss
self.codebook_weight = codebook_weight
def calculate_adaptive_weight(self, nll_loss, g_loss, last_layer):
nll_grads = torch.autograd.grad(nll_loss, last_layer, retain_graph=True)[0]
g_grads = torch.autograd.grad(g_loss, last_layer, retain_graph=True)[0]
d_weight = torch.norm(nll_grads) / (torch.norm(g_grads) + 1e-4)
d_weight = torch.clamp(d_weight, 0.0, 1e4).detach()
return d_weight.detach()
def forward(self, codebook_loss, inputs, reconstructions, optimizer_idx, global_step, last_layer=None,
logger=None, log_every=100):
# generator update
if optimizer_idx == 0:
# reconstruction loss
rec_loss = self.rec_loss(inputs.contiguous(), reconstructions.contiguous())
# perceptual loss
p_loss = self.perceptual_loss(inputs.contiguous(), reconstructions.contiguous())
p_loss = torch.mean(p_loss)
# discriminator loss
logits_fake = self.discriminator(reconstructions.contiguous())
generator_adv_loss = self.gen_adv_loss(logits_fake)
if self.disc_adaptive_weight:
null_loss = self.rec_weight * rec_loss + self.perceptual_weight * p_loss
disc_adaptive_weight = self.calculate_adaptive_weight(null_loss, generator_adv_loss, last_layer=last_layer)
else:
disc_adaptive_weight = 1
disc_weight = adopt_weight(self.disc_weight, global_step, threshold=self.discriminator_iter_start)
loss = self.rec_weight * rec_loss + \
self.perceptual_weight * p_loss + \
disc_adaptive_weight * disc_weight * generator_adv_loss + \
codebook_loss[0] + codebook_loss[1] + codebook_loss[2]
if global_step % log_every == 0:
rec_loss = self.rec_weight * rec_loss
p_loss = self.perceptual_weight * p_loss
generator_adv_loss = disc_adaptive_weight * disc_weight * generator_adv_loss
logger.info(f"(Generator) rec_loss: {rec_loss:.4f}, perceptual_loss: {p_loss:.4f}, "
f"vq_loss: {codebook_loss[0]:.4f}, commit_loss: {codebook_loss[1]:.4f}, entropy_loss: {codebook_loss[2]:.4f}, "
f"codebook_usage: {codebook_loss[3]:.4f}, generator_adv_loss: {generator_adv_loss:.4f}, "
f"disc_adaptive_weight: {disc_adaptive_weight:.4f}, disc_weight: {disc_weight:.4f}")
return loss
# discriminator update
if optimizer_idx == 1:
logits_real = self.discriminator(inputs.contiguous().detach())
logits_fake = self.discriminator(reconstructions.contiguous().detach())
disc_weight = adopt_weight(self.disc_weight, global_step, threshold=self.discriminator_iter_start)
d_adversarial_loss = disc_weight * self.disc_loss(logits_real, logits_fake)
if global_step % log_every == 0:
logits_real = logits_real.detach().mean()
logits_fake = logits_fake.detach().mean()
logger.info(f"(Discriminator) "
f"discriminator_adv_loss: {d_adversarial_loss:.4f}, disc_weight: {disc_weight:.4f}, "
f"logits_real: {logits_real:.4f}, logits_fake: {logits_fake:.4f}")
return d_adversarial_loss