imaginAIry/imaginairy/enhancers/video_interpolation/rife/msssim.py

from math import exp

import torch
from torch.nn import functional as F

device = torch.device("cuda" if torch.cuda.is_available() else "cpu")


def gaussian(window_size, sigma):
    gauss = torch.Tensor(
        [
            exp(-((x - window_size // 2) ** 2) / float(2 * sigma**2))
            for x in range(window_size)
        ]
    )
    return gauss / gauss.sum()


def create_window(window_size, channel=1):
    _1D_window = gaussian(window_size, 1.5).unsqueeze(1)
    _2D_window = (
        _1D_window.mm(_1D_window.t()).float().unsqueeze(0).unsqueeze(0).to(device)
    )
    window = _2D_window.expand(channel, 1, window_size, window_size).contiguous()
    return window


def create_window_3d(window_size, channel=1):
    _1D_window = gaussian(window_size, 1.5).unsqueeze(1)
    _2D_window = _1D_window.mm(_1D_window.t())
    _3D_window = _2D_window.unsqueeze(2) @ (_1D_window.t())
    window = (
        _3D_window.expand(1, channel, window_size, window_size, window_size)
        .contiguous()
        .to(device)
    )
    return window


def ssim(
    img1,
    img2,
    window_size=11,
    window=None,
    size_average=True,
    full=False,
    val_range=None,
):
    # Value range can be different from 255. Other common ranges are 1 (sigmoid) and 2 (tanh).
    if val_range is None:
        max_val = 255 if torch.max(img1) > 128 else 1
        min_val = -1 if torch.min(img1) < -0.5 else 0
        L = max_val - min_val
    else:
        L = val_range

    padd = 0
    (_, channel, height, width) = img1.size()
    if window is None:
        real_size = min(window_size, height, width)
        window = create_window(real_size, channel=channel).to(img1.device)

    # mu1 = F.conv2d(img1, window, padding=padd, groups=channel)
    # mu2 = F.conv2d(img2, window, padding=padd, groups=channel)
    mu1 = F.conv2d(
        F.pad(img1, (5, 5, 5, 5), mode="replicate"),
        window,
        padding=padd,
        groups=channel,
    )
    mu2 = F.conv2d(
        F.pad(img2, (5, 5, 5, 5), mode="replicate"),
        window,
        padding=padd,
        groups=channel,
    )

    mu1_sq = mu1.pow(2)
    mu2_sq = mu2.pow(2)
    mu1_mu2 = mu1 * mu2

    sigma1_sq = (
        F.conv2d(
            F.pad(img1 * img1, (5, 5, 5, 5), "replicate"),
            window,
            padding=padd,
            groups=channel,
        )
        - mu1_sq
    )
    sigma2_sq = (
        F.conv2d(
            F.pad(img2 * img2, (5, 5, 5, 5), "replicate"),
            window,
            padding=padd,
            groups=channel,
        )
        - mu2_sq
    )
    sigma12 = (
        F.conv2d(
            F.pad(img1 * img2, (5, 5, 5, 5), "replicate"),
            window,
            padding=padd,
            groups=channel,
        )
        - mu1_mu2
    )

    C1 = (0.01 * L) ** 2
    C2 = (0.03 * L) ** 2

    v1 = 2.0 * sigma12 + C2
    v2 = sigma1_sq + sigma2_sq + C2
    cs = torch.mean(v1 / v2)  # contrast sensitivity

    ssim_map = ((2 * mu1_mu2 + C1) * v1) / ((mu1_sq + mu2_sq + C1) * v2)

    ret = ssim_map.mean() if size_average else ssim_map.mean(1).mean(1).mean(1)

    if full:
        return ret, cs
    return ret


def ssim_matlab(
    img1,
    img2,
    window_size=11,
    window=None,
    size_average=True,
    full=False,
    val_range=None,
):
    # Value range can be different from 255. Other common ranges are 1 (sigmoid) and 2 (tanh).
    if val_range is None:
        max_val = 255 if torch.max(img1) > 128 else 1
        min_val = -1 if torch.min(img1) < -0.5 else 0
        L = max_val - min_val
    else:
        L = val_range

    padd = 0
    (_, _, height, width) = img1.size()
    if window is None:
        real_size = min(window_size, height, width)
        window = create_window_3d(real_size, channel=1).to(img1.device)
        # Channel is set to 1 since we consider color images as volumetric images

    img1 = img1.unsqueeze(1)
    img2 = img2.unsqueeze(1)

    mu1 = F.conv3d(
        F.pad(img1, (5, 5, 5, 5, 5, 5), mode="replicate"),
        window,
        padding=padd,
        groups=1,
    )
    mu2 = F.conv3d(
        F.pad(img2, (5, 5, 5, 5, 5, 5), mode="replicate"),
        window,
        padding=padd,
        groups=1,
    )

    mu1_sq = mu1.pow(2)
    mu2_sq = mu2.pow(2)
    mu1_mu2 = mu1 * mu2

    sigma1_sq = (
        F.conv3d(
            F.pad(img1 * img1, (5, 5, 5, 5, 5, 5), "replicate"),
            window,
            padding=padd,
            groups=1,
        )
        - mu1_sq
    )
    sigma2_sq = (
        F.conv3d(
            F.pad(img2 * img2, (5, 5, 5, 5, 5, 5), "replicate"),
            window,
            padding=padd,
            groups=1,
        )
        - mu2_sq
    )
    sigma12 = (
        F.conv3d(
            F.pad(img1 * img2, (5, 5, 5, 5, 5, 5), "replicate"),
            window,
            padding=padd,
            groups=1,
        )
        - mu1_mu2
    )

    C1 = (0.01 * L) ** 2
    C2 = (0.03 * L) ** 2

    v1 = 2.0 * sigma12 + C2
    v2 = sigma1_sq + sigma2_sq + C2
    cs = torch.mean(v1 / v2)  # contrast sensitivity

    ssim_map = ((2 * mu1_mu2 + C1) * v1) / ((mu1_sq + mu2_sq + C1) * v2)

    ret = ssim_map.mean() if size_average else ssim_map.mean(1).mean(1).mean(1)

    if full:
        return ret, cs
    return ret


def msssim(
    img1, img2, window_size=11, size_average=True, val_range=None, normalize=False
):
    device = img1.device
    weights = torch.FloatTensor([0.0448, 0.2856, 0.3001, 0.2363, 0.1333]).to(device)
    levels = weights.size()[0]
    mssim = []
    mcs = []
    for _ in range(levels):
        sim, cs = ssim(
            img1,
            img2,
            window_size=window_size,
            size_average=size_average,
            full=True,
            val_range=val_range,
        )
        mssim.append(sim)
        mcs.append(cs)

        img1 = F.avg_pool2d(img1, (2, 2))
        img2 = F.avg_pool2d(img2, (2, 2))

    mssim = torch.stack(mssim)
    mcs = torch.stack(mcs)

    # Normalize (to avoid NaNs during training unstable models, not compliant with original definition)
    if normalize:
        mssim = (mssim + 1) / 2
        mcs = (mcs + 1) / 2

    pow1 = mcs**weights
    pow2 = mssim**weights
    # From Matlab implementation https://ece.uwaterloo.ca/~z70wang/research/iwssim/
    output = torch.prod(pow1[:-1] * pow2[-1])
    return output


class SSIM(torch.nn.Module):
    def __init__(self, window_size=11, size_average=True, val_range=None):
        super().__init__()
        self.window_size = window_size
        self.size_average = size_average
        self.val_range = val_range

        # Assume 3 channel for SSIM
        self.channel = 3
        self.window = create_window(window_size, channel=self.channel)

    def forward(self, img1, img2):
        (_, channel, _, _) = img1.size()

        if channel == self.channel and self.window.dtype == img1.dtype:
            window = self.window
        else:
            window = (
                create_window(self.window_size, channel)
                .to(img1.device)
                .type(img1.dtype)
            )
            self.window = window
            self.channel = channel

        _ssim = ssim(
            img1,
            img2,
            window=window,
            window_size=self.window_size,
            size_average=self.size_average,
        )
        dssim = (1 - _ssim) / 2
        return dssim


class MSSSIM(torch.nn.Module):
    def __init__(self, window_size=11, size_average=True, channel=3):
        super().__init__()
        self.window_size = window_size
        self.size_average = size_average
        self.channel = channel

    def forward(self, img1, img2):
        return msssim(
            img1, img2, window_size=self.window_size, size_average=self.size_average
        )