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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 |