src/vqvaes/titok/modules/lpips.py

"""This file contains code for LPIPS.

This file may have been modified by Bytedance Ltd. and/or its affiliates (“Bytedance's Modifications”).
All Bytedance's Modifications are Copyright (year) Bytedance Ltd. and/or its affiliates.

Reference:
    https://github.com/richzhang/PerceptualSimilarity/
    https://github.com/CompVis/taming-transformers/blob/master/taming/modules/losses/lpips.py
    https://github.com/CompVis/taming-transformers/blob/master/taming/util.py
"""

import os
import hashlib
import requests
from collections import namedtuple
from tqdm import tqdm

import torch
import torch.nn as nn

from torchvision import models

_LPIPS_MEAN = [-0.030, -0.088, -0.188]
_LPIPS_STD = [0.458, 0.448, 0.450]


URL_MAP = {"vgg_lpips": "https://heibox.uni-heidelberg.de/f/607503859c864bc1b30b/?dl=1"}

CKPT_MAP = {"vgg_lpips": "vgg.pth"}

MD5_MAP = {"vgg_lpips": "d507d7349b931f0638a25a48a722f98a"}


def download(url, local_path, chunk_size=1024):
    os.makedirs(os.path.split(local_path)[0], exist_ok=True)
    with requests.get(url, stream=True) as r:
        total_size = int(r.headers.get("content-length", 0))
        with tqdm(total=total_size, unit="B", unit_scale=True) as pbar:
            with open(local_path, "wb") as f:
                for data in r.iter_content(chunk_size=chunk_size):
                    if data:
                        f.write(data)
                        pbar.update(chunk_size)


def md5_hash(path):
    with open(path, "rb") as f:
        content = f.read()
    return hashlib.md5(content).hexdigest()


def get_ckpt_path(name, root, check=False):
    assert name in URL_MAP
    path = os.path.join(root, CKPT_MAP[name])
    if not os.path.exists(path) or (check and not md5_hash(path) == MD5_MAP[name]):
        print("Downloading {} model from {} to {}".format(name, URL_MAP[name], path))
        download(URL_MAP[name], path)
        md5 = md5_hash(path)
        assert md5 == MD5_MAP[name], md5
    return path


class LPIPS(nn.Module):
    # Learned perceptual metric.
    def __init__(self, use_dropout=True):
        super().__init__()
        self.scaling_layer = ScalingLayer()
        self.chns = [64, 128, 256, 512, 512]  # vg16 features
        self.net = vgg16(pretrained=True, requires_grad=False)
        self.lin0 = NetLinLayer(self.chns[0], use_dropout=use_dropout)
        self.lin1 = NetLinLayer(self.chns[1], use_dropout=use_dropout)
        self.lin2 = NetLinLayer(self.chns[2], use_dropout=use_dropout)
        self.lin3 = NetLinLayer(self.chns[3], use_dropout=use_dropout)
        self.lin4 = NetLinLayer(self.chns[4], use_dropout=use_dropout)
        self.load_pretrained()
        for param in self.parameters():
            param.requires_grad = False

    def load_pretrained(self):
        workspace = os.environ.get("WORKSPACE", "")
        VGG_PATH = get_ckpt_path(
            "vgg_lpips", os.path.join(workspace, "models/vgg_lpips.pth"), check=True
        )
        self.load_state_dict(
            torch.load(VGG_PATH, map_location=torch.device("cpu")), strict=False
        )

    def forward(self, input, target):
        # Notably, the LPIPS w/ pre-trained weights expect the input in the range of [-1, 1].
        # However, our codebase assumes all inputs are in range of [0, 1], and thus a scaling is needed.
        input = input * 2.0 - 1.0
        target = target * 2.0 - 1.0
        in0_input, in1_input = (self.scaling_layer(input), self.scaling_layer(target))
        outs0, outs1 = self.net(in0_input), self.net(in1_input)
        feats0, feats1, diffs = {}, {}, {}
        lins = [self.lin0, self.lin1, self.lin2, self.lin3, self.lin4]
        for kk in range(len(self.chns)):
            feats0[kk], feats1[kk] = normalize_tensor(outs0[kk]), normalize_tensor(
                outs1[kk]
            )
            diffs[kk] = (feats0[kk] - feats1[kk]) ** 2

        res = [
            spatial_average(lins[kk].model(diffs[kk]), keepdim=True)
            for kk in range(len(self.chns))
        ]
        val = res[0]
        for l in range(1, len(self.chns)):
            val += res[l]
        return val


class ScalingLayer(nn.Module):
    def __init__(self):
        super(ScalingLayer, self).__init__()
        self.register_buffer("shift", torch.Tensor(_LPIPS_MEAN)[None, :, None, None])
        self.register_buffer("scale", torch.Tensor(_LPIPS_STD)[None, :, None, None])

    def forward(self, inp):
        return (inp - self.shift) / self.scale


class NetLinLayer(nn.Module):
    """A single linear layer which does a 1x1 conv."""

    def __init__(self, chn_in, chn_out=1, use_dropout=False):
        super(NetLinLayer, self).__init__()
        layers = (
            [
                nn.Dropout(),
            ]
            if (use_dropout)
            else []
        )
        layers += [
            nn.Conv2d(chn_in, chn_out, 1, stride=1, padding=0, bias=False),
        ]
        self.model = nn.Sequential(*layers)


class vgg16(torch.nn.Module):
    def __init__(self, requires_grad=False, pretrained=True):
        super(vgg16, self).__init__()
        vgg_pretrained_features = models.vgg16(
            weights=models.VGG16_Weights.IMAGENET1K_V1
        ).features
        self.slice1 = torch.nn.Sequential()
        self.slice2 = torch.nn.Sequential()
        self.slice3 = torch.nn.Sequential()
        self.slice4 = torch.nn.Sequential()
        self.slice5 = torch.nn.Sequential()
        self.N_slices = 5
        for x in range(4):
            self.slice1.add_module(str(x), vgg_pretrained_features[x])
        for x in range(4, 9):
            self.slice2.add_module(str(x), vgg_pretrained_features[x])
        for x in range(9, 16):
            self.slice3.add_module(str(x), vgg_pretrained_features[x])
        for x in range(16, 23):
            self.slice4.add_module(str(x), vgg_pretrained_features[x])
        for x in range(23, 30):
            self.slice5.add_module(str(x), vgg_pretrained_features[x])
        if not requires_grad:
            for param in self.parameters():
                param.requires_grad = False

    def forward(self, X):
        h = self.slice1(X)
        h_relu1_2 = h
        h = self.slice2(h)
        h_relu2_2 = h
        h = self.slice3(h)
        h_relu3_3 = h
        h = self.slice4(h)
        h_relu4_3 = h
        h = self.slice5(h)
        h_relu5_3 = h
        vgg_outputs = namedtuple(
            "VggOutputs", ["relu1_2", "relu2_2", "relu3_3", "relu4_3", "relu5_3"]
        )
        out = vgg_outputs(h_relu1_2, h_relu2_2, h_relu3_3, h_relu4_3, h_relu5_3)
        return out


def normalize_tensor(x, eps=1e-10):
    norm_factor = torch.sqrt(torch.sum(x**2, dim=1, keepdim=True))
    return x / (norm_factor + eps)


def spatial_average(x, keepdim=True):
    return x.mean([2, 3], keepdim=keepdim)