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cycle_gan_model.py
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cycle_gan_model.py
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import torch
import itertools
from util.image_pool import ImagePool
from .base_model import BaseModel
from . import networks
class CycleGANModel(BaseModel):
def name(self):
return 'CycleGANModel'
@staticmethod
def modify_commandline_options(parser, is_train=True):
# default CycleGAN did not use dropout
parser.set_defaults(no_dropout=True)
if is_train:
parser.add_argument('--lambda_A', type=float, default=10.0, help='weight for cycle loss (A -> B -> A)')
parser.add_argument('--lambda_B', type=float, default=10.0,
help='weight for cycle loss (B -> A -> B)')
parser.add_argument('--lambda_identity', type=float, default=0.5, help='use identity mapping. Setting lambda_identity other than 0 has an effect of scaling the weight of the identity mapping loss. For example, if the weight of the identity loss should be 10 times smaller than the weight of the reconstruction loss, please set lambda_identity = 0.1')
return parser
def initialize(self, opt):
BaseModel.initialize(self, opt)
# specify the training losses you want to print out. The program will call base_model.get_current_losses
self.loss_names = ['D_A', 'G_A', 'cycle_A', 'idt_A', 'D_B', 'G_B', 'cycle_B', 'idt_B']
# specify the images you want to save/display. The program will call base_model.get_current_visuals
visual_names_A = ['real_A', 'fake_B', 'rec_A']
visual_names_B = ['real_B', 'fake_A', 'rec_B']
if self.isTrain and self.opt.lambda_identity > 0.0:
visual_names_A.append('idt_A')
visual_names_B.append('idt_B')
self.visual_names = visual_names_A + visual_names_B
# specify the models you want to save to the disk. The program will call base_model.save_networks and base_model.load_networks
if self.isTrain:
self.model_names = ['G_A', 'G_B', 'D_A', 'D_B']
else: # during test time, only load Gs
self.model_names = ['G_A', 'G_B']
# load/define networks
# The naming conversion is different from those used in the paper
# Code (paper): G_A (G), G_B (F), D_A (D_Y), D_B (D_X)
self.netG_A = networks.define_G(opt.input_nc, opt.output_nc, opt.ngf, opt.netG, opt.norm,
not opt.no_dropout, opt.init_type, opt.init_gain, self.gpu_ids)
self.netG_B = networks.define_G(opt.output_nc, opt.input_nc, opt.ngf, opt.netG, opt.norm,
not opt.no_dropout, opt.init_type, opt.init_gain, self.gpu_ids)
if self.isTrain:
use_sigmoid = opt.no_lsgan
self.netD_A = networks.define_D(opt.output_nc, opt.ndf, opt.netD,
opt.n_layers_D, opt.norm, use_sigmoid, opt.init_type, opt.init_gain, self.gpu_ids)
self.netD_B = networks.define_D(opt.input_nc, opt.ndf, opt.netD,
opt.n_layers_D, opt.norm, use_sigmoid, opt.init_type, opt.init_gain, self.gpu_ids)
if self.isTrain:
self.fake_A_pool = ImagePool(opt.pool_size)
self.fake_B_pool = ImagePool(opt.pool_size)
# define loss functions
self.criterionGAN = networks.GANLoss(use_lsgan=not opt.no_lsgan).to(self.device)
self.criterionCycle = torch.nn.L1Loss()
self.criterionIdt = torch.nn.L1Loss()
# initialize optimizers
self.optimizer_G = torch.optim.Adam(itertools.chain(self.netG_A.parameters(), self.netG_B.parameters()),
lr=opt.lr, betas=(opt.beta1, 0.999))
self.optimizer_D = torch.optim.Adam(itertools.chain(self.netD_A.parameters(), self.netD_B.parameters()),
lr=opt.lr, betas=(opt.beta1, 0.999))
self.optimizers = []
self.optimizers.append(self.optimizer_G)
self.optimizers.append(self.optimizer_D)
def set_input(self, input):
AtoB = self.opt.direction == 'AtoB'
self.real_A = input['A' if AtoB else 'B'].to(self.device)
self.real_B = input['B' if AtoB else 'A'].to(self.device)
self.image_paths = input['A_paths' if AtoB else 'B_paths']
def forward(self):
self.fake_B = self.netG_A(self.real_A)
self.rec_A = self.netG_B(self.fake_B)
self.fake_A = self.netG_B(self.real_B)
self.rec_B = self.netG_A(self.fake_A)
def backward_D_basic(self, netD, real, fake):
# Real
pred_real = netD(real)
loss_D_real = self.criterionGAN(pred_real, True)
# Fake
pred_fake = netD(fake.detach())
loss_D_fake = self.criterionGAN(pred_fake, False)
# Combined loss
loss_D = (loss_D_real + loss_D_fake) * 0.5
# backward
loss_D.backward()
return loss_D
def backward_D_A(self):
fake_B = self.fake_B_pool.query(self.fake_B)
self.loss_D_A = self.backward_D_basic(self.netD_A, self.real_B, fake_B)
def backward_D_B(self):
fake_A = self.fake_A_pool.query(self.fake_A)
self.loss_D_B = self.backward_D_basic(self.netD_B, self.real_A, fake_A)
def backward_G(self):
lambda_idt = self.opt.lambda_identity
lambda_A = self.opt.lambda_A
lambda_B = self.opt.lambda_B
# Identity loss
if lambda_idt > 0:
# G_A should be identity if real_B is fed.
self.idt_A = self.netG_A(self.real_B)
self.loss_idt_A = self.criterionIdt(self.idt_A, self.real_B) * lambda_B * lambda_idt
# G_B should be identity if real_A is fed.
self.idt_B = self.netG_B(self.real_A)
self.loss_idt_B = self.criterionIdt(self.idt_B, self.real_A) * lambda_A * lambda_idt
else:
self.loss_idt_A = 0
self.loss_idt_B = 0
# GAN loss D_A(G_A(A))
self.loss_G_A = self.criterionGAN(self.netD_A(self.fake_B), True)
# GAN loss D_B(G_B(B))
self.loss_G_B = self.criterionGAN(self.netD_B(self.fake_A), True)
# Forward cycle loss
self.loss_cycle_A = self.criterionCycle(self.rec_A, self.real_A) * lambda_A
# Backward cycle loss
self.loss_cycle_B = self.criterionCycle(self.rec_B, self.real_B) * lambda_B
# combined loss
self.loss_G = self.loss_G_A + self.loss_G_B + self.loss_cycle_A + self.loss_cycle_B + self.loss_idt_A + self.loss_idt_B
self.loss_G.backward()
def optimize_parameters(self):
# forward
self.forward()
# G_A and G_B
self.set_requires_grad([self.netD_A, self.netD_B], False)
self.optimizer_G.zero_grad()
self.backward_G()
self.optimizer_G.step()
# D_A and D_B
self.set_requires_grad([self.netD_A, self.netD_B], True)
self.optimizer_D.zero_grad()
self.backward_D_A()
self.backward_D_B()
self.optimizer_D.step()