# Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES. All rights reserved. # # NVIDIA CORPORATION and its licensors retain all intellectual property # and proprietary rights in and to this software, related documentation # and any modifications thereto. Any use, reproduction, disclosure or # distribution of this software and related documentation without an express # license agreement from NVIDIA CORPORATION is strictly prohibited. """Loss functions.""" import numpy as np import torch from torch_utils import training_stats from torch_utils.ops import conv2d_gradfix from torch_utils.ops import upfirdn2d #---------------------------------------------------------------------------- class Loss: def accumulate_gradients(self, phase, real_img, real_c, gen_z, gen_c, gain, cur_nimg): # to be overridden by subclass raise NotImplementedError() #---------------------------------------------------------------------------- class StyleGAN2Loss(Loss): def __init__(self, device, G, D, augment_pipe=None, r1_gamma=10, style_mixing_prob=0, pl_weight=0, pl_batch_shrink=2, pl_decay=0.01, pl_no_weight_grad=False, blur_init_sigma=0, blur_fade_kimg=0): super().__init__() self.device = device self.G = G self.D = D self.augment_pipe = augment_pipe self.r1_gamma = r1_gamma self.style_mixing_prob = style_mixing_prob self.pl_weight = pl_weight self.pl_batch_shrink = pl_batch_shrink self.pl_decay = pl_decay self.pl_no_weight_grad = pl_no_weight_grad self.pl_mean = torch.zeros([], device=device) self.blur_init_sigma = blur_init_sigma self.blur_fade_kimg = blur_fade_kimg def run_G(self, z, c, update_emas=False): ws = self.G.mapping(z, c, update_emas=update_emas) if self.style_mixing_prob > 0: with torch.autograd.profiler.record_function('style_mixing'): cutoff = torch.empty([], dtype=torch.int64, device=ws.device).random_(1, ws.shape[1]) cutoff = torch.where(torch.rand([], device=ws.device) < self.style_mixing_prob, cutoff, torch.full_like(cutoff, ws.shape[1])) ws[:, cutoff:] = self.G.mapping(torch.randn_like(z), c, update_emas=False)[:, cutoff:] img = self.G.synthesis(ws, update_emas=update_emas) return img, ws def run_D(self, img, c, blur_sigma=0, update_emas=False): blur_size = np.floor(blur_sigma * 3) if blur_size > 0: with torch.autograd.profiler.record_function('blur'): f = torch.arange(-blur_size, blur_size + 1, device=img.device).div(blur_sigma).square().neg().exp2() img = upfirdn2d.filter2d(img, f / f.sum()) if self.augment_pipe is not None: img = self.augment_pipe(img) logits = self.D(img, c, update_emas=update_emas) return logits def accumulate_gradients(self, phase, real_img, real_c, gen_z, gen_c, gain, cur_nimg): assert phase in ['Gmain', 'Greg', 'Gboth', 'Dmain', 'Dreg', 'Dboth'] if self.pl_weight == 0: phase = {'Greg': 'none', 'Gboth': 'Gmain'}.get(phase, phase) if self.r1_gamma == 0: phase = {'Dreg': 'none', 'Dboth': 'Dmain'}.get(phase, phase) blur_sigma = max(1 - cur_nimg / (self.blur_fade_kimg * 1e3), 0) * self.blur_init_sigma if self.blur_fade_kimg > 0 else 0 # Gmain: Maximize logits for generated images. if phase in ['Gmain', 'Gboth']: with torch.autograd.profiler.record_function('Gmain_forward'): gen_img, _gen_ws = self.run_G(gen_z, gen_c) gen_logits = self.run_D(gen_img, gen_c, blur_sigma=blur_sigma) training_stats.report('Loss/scores/fake', gen_logits) training_stats.report('Loss/signs/fake', gen_logits.sign()) loss_Gmain = torch.nn.functional.softplus(-gen_logits) # -log(sigmoid(gen_logits)) training_stats.report('Loss/G/loss', loss_Gmain) with torch.autograd.profiler.record_function('Gmain_backward'): loss_Gmain.mean().mul(gain).backward() # Gpl: Apply path length regularization. if phase in ['Greg', 'Gboth']: with torch.autograd.profiler.record_function('Gpl_forward'): batch_size = gen_z.shape[0] // self.pl_batch_shrink gen_img, gen_ws = self.run_G(gen_z[:batch_size], gen_c[:batch_size]) pl_noise = torch.randn_like(gen_img) / np.sqrt(gen_img.shape[2] * gen_img.shape[3]) with torch.autograd.profiler.record_function('pl_grads'), conv2d_gradfix.no_weight_gradients(self.pl_no_weight_grad): pl_grads = torch.autograd.grad(outputs=[(gen_img * pl_noise).sum()], inputs=[gen_ws], create_graph=True, only_inputs=True)[0] pl_lengths = pl_grads.square().sum(2).mean(1).sqrt() pl_mean = self.pl_mean.lerp(pl_lengths.mean(), self.pl_decay) self.pl_mean.copy_(pl_mean.detach()) pl_penalty = (pl_lengths - pl_mean).square() training_stats.report('Loss/pl_penalty', pl_penalty) loss_Gpl = pl_penalty * self.pl_weight training_stats.report('Loss/G/reg', loss_Gpl) with torch.autograd.profiler.record_function('Gpl_backward'): loss_Gpl.mean().mul(gain).backward() # Dmain: Minimize logits for generated images. loss_Dgen = 0 if phase in ['Dmain', 'Dboth']: with torch.autograd.profiler.record_function('Dgen_forward'): gen_img, _gen_ws = self.run_G(gen_z, gen_c, update_emas=True) gen_logits = self.run_D(gen_img, gen_c, blur_sigma=blur_sigma, update_emas=True) training_stats.report('Loss/scores/fake', gen_logits) training_stats.report('Loss/signs/fake', gen_logits.sign()) loss_Dgen = torch.nn.functional.softplus(gen_logits) # -log(1 - sigmoid(gen_logits)) with torch.autograd.profiler.record_function('Dgen_backward'): loss_Dgen.mean().mul(gain).backward() # Dmain: Maximize logits for real images. # Dr1: Apply R1 regularization. if phase in ['Dmain', 'Dreg', 'Dboth']: name = 'Dreal' if phase == 'Dmain' else 'Dr1' if phase == 'Dreg' else 'Dreal_Dr1' with torch.autograd.profiler.record_function(name + '_forward'): real_img_tmp = real_img.detach().requires_grad_(phase in ['Dreg', 'Dboth']) real_logits = self.run_D(real_img_tmp, real_c, blur_sigma=blur_sigma) training_stats.report('Loss/scores/real', real_logits) training_stats.report('Loss/signs/real', real_logits.sign()) loss_Dreal = 0 if phase in ['Dmain', 'Dboth']: loss_Dreal = torch.nn.functional.softplus(-real_logits) # -log(sigmoid(real_logits)) training_stats.report('Loss/D/loss', loss_Dgen + loss_Dreal) loss_Dr1 = 0 if phase in ['Dreg', 'Dboth']: with torch.autograd.profiler.record_function('r1_grads'), conv2d_gradfix.no_weight_gradients(): r1_grads = torch.autograd.grad(outputs=[real_logits.sum()], inputs=[real_img_tmp], create_graph=True, only_inputs=True)[0] r1_penalty = r1_grads.square().sum([1,2,3]) loss_Dr1 = r1_penalty * (self.r1_gamma / 2) training_stats.report('Loss/r1_penalty', r1_penalty) training_stats.report('Loss/D/reg', loss_Dr1) with torch.autograd.profiler.record_function(name + '_backward'): (loss_Dreal + loss_Dr1).mean().mul(gain).backward() #----------------------------------------------------------------------------