generative_models/sgm/modules/autoencoding/losses/discriminator_loss.py

from typing import Dict, Iterator, List, Optional, Tuple, Union

import numpy as np
import torch
import torch.nn as nn
import torchvision
from einops import rearrange
from matplotlib import colormaps
from matplotlib import pyplot as plt

from ....util import default, instantiate_from_config
from ..lpips.loss.lpips import LPIPS
from ..lpips.model.model import weights_init
from ..lpips.vqperceptual import hinge_d_loss, vanilla_d_loss


class GeneralLPIPSWithDiscriminator(nn.Module):
    def __init__(
        self,
        disc_start: int,
        logvar_init: float = 0.0,
        disc_num_layers: int = 3,
        disc_in_channels: int = 3,
        disc_factor: float = 1.0,
        disc_weight: float = 1.0,
        perceptual_weight: float = 1.0,
        disc_loss: str = "hinge",
        scale_input_to_tgt_size: bool = False,
        dims: int = 2,
        learn_logvar: bool = False,
        regularization_weights: Union[None, Dict[str, float]] = None,
        additional_log_keys: Optional[List[str]] = None,
        discriminator_config: Optional[Dict] = None,
    ):
        super().__init__()
        self.dims = dims
        if self.dims > 2:
            print(
                f"running with dims={dims}. This means that for perceptual loss "
                f"calculation, the LPIPS loss will be applied to each frame "
                f"independently."
            )
        self.scale_input_to_tgt_size = scale_input_to_tgt_size
        assert disc_loss in ["hinge", "vanilla"]
        self.perceptual_loss = LPIPS().eval()
        self.perceptual_weight = perceptual_weight
        # output log variance
        self.logvar = nn.Parameter(
            torch.full((), logvar_init), requires_grad=learn_logvar
        )
        self.learn_logvar = learn_logvar

        discriminator_config = default(
            discriminator_config,
            {
                "target": "sgm.modules.autoencoding.lpips.model.model.NLayerDiscriminator",
                "params": {
                    "input_nc": disc_in_channels,
                    "n_layers": disc_num_layers,
                    "use_actnorm": False,
                },
            },
        )

        self.discriminator = instantiate_from_config(discriminator_config).apply(
            weights_init
        )
        self.discriminator_iter_start = disc_start
        self.disc_loss = hinge_d_loss if disc_loss == "hinge" else vanilla_d_loss
        self.disc_factor = disc_factor
        self.discriminator_weight = disc_weight
        self.regularization_weights = default(regularization_weights, {})

        self.forward_keys = [
            "optimizer_idx",
            "global_step",
            "last_layer",
            "split",
            "regularization_log",
        ]

        self.additional_log_keys = set(default(additional_log_keys, []))
        self.additional_log_keys.update(set(self.regularization_weights.keys()))

    def get_trainable_parameters(self) -> Iterator[nn.Parameter]:
        return self.discriminator.parameters()

    def get_trainable_autoencoder_parameters(self) -> Iterator[nn.Parameter]:
        if self.learn_logvar:
            yield self.logvar
        yield from ()

    @torch.no_grad()
    def log_images(
        self, inputs: torch.Tensor, reconstructions: torch.Tensor
    ) -> Dict[str, torch.Tensor]:
        # calc logits of real/fake
        logits_real = self.discriminator(inputs.contiguous().detach())
        if len(logits_real.shape) < 4:
            # Non patch-discriminator
            return dict()
        logits_fake = self.discriminator(reconstructions.contiguous().detach())
        # -> (b, 1, h, w)

        # parameters for colormapping
        high = max(logits_fake.abs().max(), logits_real.abs().max()).item()
        cmap = colormaps["PiYG"]  # diverging colormap

        def to_colormap(logits: torch.Tensor) -> torch.Tensor:
            """(b, 1, ...) -> (b, 3, ...)"""
            logits = (logits + high) / (2 * high)
            logits_np = cmap(logits.cpu().numpy())[..., :3]  # truncate alpha channel
            # -> (b, 1, ..., 3)
            logits = torch.from_numpy(logits_np).to(logits.device)
            return rearrange(logits, "b 1 ... c -> b c ...")

        logits_real = torch.nn.functional.interpolate(
            logits_real,
            size=inputs.shape[-2:],
            mode="nearest",
            antialias=False,
        )
        logits_fake = torch.nn.functional.interpolate(
            logits_fake,
            size=reconstructions.shape[-2:],
            mode="nearest",
            antialias=False,
        )

        # alpha value of logits for overlay
        alpha_real = torch.abs(logits_real) / high
        alpha_fake = torch.abs(logits_fake) / high
        # -> (b, 1, h, w) in range [0, 0.5]
        # alpha value of lines don't really matter, since the values are the same
        # for both images and logits anyway
        grid_alpha_real = torchvision.utils.make_grid(alpha_real, nrow=4)
        grid_alpha_fake = torchvision.utils.make_grid(alpha_fake, nrow=4)
        grid_alpha = 0.8 * torch.cat((grid_alpha_real, grid_alpha_fake), dim=1)
        # -> (1, h, w)
        # blend logits and images together

        # prepare logits for plotting
        logits_real = to_colormap(logits_real)
        logits_fake = to_colormap(logits_fake)
        # resize logits
        # -> (b, 3, h, w)

        # make some grids
        # add all logits to one plot
        logits_real = torchvision.utils.make_grid(logits_real, nrow=4)
        logits_fake = torchvision.utils.make_grid(logits_fake, nrow=4)
        # I just love how torchvision calls the number of columns `nrow`
        grid_logits = torch.cat((logits_real, logits_fake), dim=1)
        # -> (3, h, w)

        grid_images_real = torchvision.utils.make_grid(0.5 * inputs + 0.5, nrow=4)
        grid_images_fake = torchvision.utils.make_grid(
            0.5 * reconstructions + 0.5, nrow=4
        )
        grid_images = torch.cat((grid_images_real, grid_images_fake), dim=1)
        # -> (3, h, w) in range [0, 1]

        grid_blend = grid_alpha * grid_logits + (1 - grid_alpha) * grid_images

        # Create labeled colorbar
        dpi = 100
        height = 128 / dpi
        width = grid_logits.shape[2] / dpi
        fig, ax = plt.subplots(figsize=(width, height), dpi=dpi)
        img = ax.imshow(np.array([[-high, high]]), cmap=cmap)
        plt.colorbar(
            img,
            cax=ax,
            orientation="horizontal",
            fraction=0.9,
            aspect=width / height,
            pad=0.0,
        )
        img.set_visible(False)
        fig.tight_layout()
        fig.canvas.draw()
        # manually convert figure to numpy
        cbar_np = np.frombuffer(fig.canvas.tostring_rgb(), dtype=np.uint8)
        cbar_np = cbar_np.reshape(fig.canvas.get_width_height()[::-1] + (3,))
        cbar = torch.from_numpy(cbar_np.copy()).to(grid_logits.dtype) / 255.0
        cbar = rearrange(cbar, "h w c -> c h w").to(grid_logits.device)

        # Add colorbar to plot
        annotated_grid = torch.cat((grid_logits, cbar), dim=1)
        blended_grid = torch.cat((grid_blend, cbar), dim=1)
        return {
            "vis_logits": 2 * annotated_grid[None, ...] - 1,
            "vis_logits_blended": 2 * blended_grid[None, ...] - 1,
        }

    def calculate_adaptive_weight(
        self, nll_loss: torch.Tensor, g_loss: torch.Tensor, last_layer: torch.Tensor
    ) -> torch.Tensor:
        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()
        d_weight = d_weight * self.discriminator_weight
        return d_weight

    def forward(
        self,
        inputs: torch.Tensor,
        reconstructions: torch.Tensor,
        *,  # added because I changed the order here
        regularization_log: Dict[str, torch.Tensor],
        optimizer_idx: int,
        global_step: int,
        last_layer: torch.Tensor,
        split: str = "train",
        weights: Union[None, float, torch.Tensor] = None,
    ) -> Tuple[torch.Tensor, dict]:
        if self.scale_input_to_tgt_size:
            inputs = torch.nn.functional.interpolate(
                inputs, reconstructions.shape[2:], mode="bicubic", antialias=True
            )

        if self.dims > 2:
            inputs, reconstructions = map(
                lambda x: rearrange(x, "b c t h w -> (b t) c h w"),
                (inputs, reconstructions),
            )

        rec_loss = torch.abs(inputs.contiguous() - reconstructions.contiguous())
        if self.perceptual_weight > 0:
            p_loss = self.perceptual_loss(
                inputs.contiguous(), reconstructions.contiguous()
            )
            rec_loss = rec_loss + self.perceptual_weight * p_loss

        nll_loss, weighted_nll_loss = self.get_nll_loss(rec_loss, weights)

        # now the GAN part
        if optimizer_idx == 0:
            # generator update
            if global_step >= self.discriminator_iter_start or not self.training:
                logits_fake = self.discriminator(reconstructions.contiguous())
                g_loss = -torch.mean(logits_fake)
                if self.training:
                    d_weight = self.calculate_adaptive_weight(
                        nll_loss, g_loss, last_layer=last_layer
                    )
                else:
                    d_weight = torch.tensor(1.0)
            else:
                d_weight = torch.tensor(0.0)
                g_loss = torch.tensor(0.0, requires_grad=True)

            loss = weighted_nll_loss + d_weight * self.disc_factor * g_loss
            log = dict()
            for k in regularization_log:
                if k in self.regularization_weights:
                    loss = loss + self.regularization_weights[k] * regularization_log[k]
                if k in self.additional_log_keys:
                    log[f"{split}/{k}"] = regularization_log[k].detach().float().mean()

            log.update(
                {
                    f"{split}/loss/total": loss.clone().detach().mean(),
                    f"{split}/loss/nll": nll_loss.detach().mean(),
                    f"{split}/loss/rec": rec_loss.detach().mean(),
                    f"{split}/loss/g": g_loss.detach().mean(),
                    f"{split}/scalars/logvar": self.logvar.detach(),
                    f"{split}/scalars/d_weight": d_weight.detach(),
                }
            )

            return loss, log
        elif optimizer_idx == 1:
            # second pass for discriminator update
            logits_real = self.discriminator(inputs.contiguous().detach())
            logits_fake = self.discriminator(reconstructions.contiguous().detach())

            if global_step >= self.discriminator_iter_start or not self.training:
                d_loss = self.disc_factor * self.disc_loss(logits_real, logits_fake)
            else:
                d_loss = torch.tensor(0.0, requires_grad=True)

            log = {
                f"{split}/loss/disc": d_loss.clone().detach().mean(),
                f"{split}/logits/real": logits_real.detach().mean(),
                f"{split}/logits/fake": logits_fake.detach().mean(),
            }
            return d_loss, log
        else:
            raise NotImplementedError(f"Unknown optimizer_idx {optimizer_idx}")

    def get_nll_loss(
        self,
        rec_loss: torch.Tensor,
        weights: Optional[Union[float, torch.Tensor]] = None,
    ) -> Tuple[torch.Tensor, torch.Tensor]:
        nll_loss = rec_loss / torch.exp(self.logvar) + self.logvar
        weighted_nll_loss = nll_loss
        if weights is not None:
            weighted_nll_loss = weights * nll_loss
        weighted_nll_loss = torch.sum(weighted_nll_loss) / weighted_nll_loss.shape[0]
        nll_loss = torch.sum(nll_loss) / nll_loss.shape[0]

        return nll_loss, weighted_nll_loss