import random
from functools import partial

import albumentations
import cv2
from . import utils_image as util
import numpy as np
import scipy
import scipy.stats as ss
import torch
from scipy import ndimage
from scipy.interpolate import interp2d
from scipy.linalg import orth
"""
# --------------------------------------------
# Super-Resolution
# --------------------------------------------
#
# Kai Zhang (cskaizhang@gmail.com)
# https://github.com/cszn
# From 2019/03--2021/08
# --------------------------------------------
"""


def modcrop_np(img, sf):
    '''
    Args:
        img: numpy image, WxH or WxHxC
        sf: scale factor
    Return:
        cropped image
    '''
    w, h = img.shape[:2]
    im = np.copy(img)
    return im[:w - w % sf, :h - h % sf, ...]


"""
# --------------------------------------------
# anisotropic Gaussian kernels
# --------------------------------------------
"""


def analytic_kernel(k):
    """Calculate the X4 kernel from the X2 kernel (for proof see appendix in paper)"""
    k_size = k.shape[0]
    # Calculate the big kernels size
    big_k = np.zeros((3 * k_size - 2, 3 * k_size - 2))
    # Loop over the small kernel to fill the big one
    for r in range(k_size):
        for c in range(k_size):
            big_k[2 * r:2 * r + k_size, 2 * c:2 * c + k_size] += k[r, c] * k
    # Crop the edges of the big kernel to ignore very small values and increase run time of SR
    crop = k_size // 2
    cropped_big_k = big_k[crop:-crop, crop:-crop]
    # Normalize to 1
    return cropped_big_k / cropped_big_k.sum()


def anisotropic_Gaussian(ksize=15, theta=np.pi, l1=6, l2=6):
    """ generate an anisotropic Gaussian kernel
    Args:
        ksize : e.g., 15, kernel size
        theta : [0,  pi], rotation angle range
        l1    : [0.1,50], scaling of eigenvalues
        l2    : [0.1,l1], scaling of eigenvalues
        If l1 = l2, will get an isotropic Gaussian kernel.
    Returns:
        k     : kernel
    """

    v = np.dot(
        np.array([[np.cos(theta), -np.sin(theta)],
                  [np.sin(theta), np.cos(theta)]]), np.array([1., 0.]))
    V = np.array([[v[0], v[1]], [v[1], -v[0]]])
    D = np.array([[l1, 0], [0, l2]])
    Sigma = np.dot(np.dot(V, D), np.linalg.inv(V))
    k = gm_blur_kernel(mean=[0, 0], cov=Sigma, size=ksize)

    return k


def gm_blur_kernel(mean, cov, size=15):
    center = size / 2.0 + 0.5
    k = np.zeros([size, size])
    for y in range(size):
        for x in range(size):
            cy = y - center + 1
            cx = x - center + 1
            k[y, x] = ss.multivariate_normal.pdf([cx, cy], mean=mean, cov=cov)

    k = k / np.sum(k)
    return k


def shift_pixel(x, sf, upper_left=True):
    """shift pixel for super-resolution with different scale factors
    Args:
        x: WxHxC or WxH
        sf: scale factor
        upper_left: shift direction
    """
    h, w = x.shape[:2]
    shift = (sf - 1) * 0.5
    xv, yv = np.arange(0, w, 1.0), np.arange(0, h, 1.0)
    if upper_left:
        x1 = xv + shift
        y1 = yv + shift
    else:
        x1 = xv - shift
        y1 = yv - shift

    x1 = np.clip(x1, 0, w - 1)
    y1 = np.clip(y1, 0, h - 1)

    if x.ndim == 2:
        x = interp2d(xv, yv, x)(x1, y1)
    if x.ndim == 3:
        for i in range(x.shape[-1]):
            x[:, :, i] = interp2d(xv, yv, x[:, :, i])(x1, y1)

    return x


def blur(x, k):
    '''
    x: image, NxcxHxW
    k: kernel, Nx1xhxw
    '''
    n, c = x.shape[:2]
    p1, p2 = (k.shape[-2] - 1) // 2, (k.shape[-1] - 1) // 2
    x = torch.nn.functional.pad(x, pad=(p1, p2, p1, p2), mode='replicate')
    k = k.repeat(1, c, 1, 1)
    k = k.view(-1, 1, k.shape[2], k.shape[3])
    x = x.view(1, -1, x.shape[2], x.shape[3])
    x = torch.nn.functional.conv2d(
        x, k, bias=None, stride=1, padding=0, groups=n * c)
    x = x.view(n, c, x.shape[2], x.shape[3])

    return x


def gen_kernel(
        k_size=np.array([15, 15]),
        scale_factor=np.array([4, 4]),
        min_var=0.6,
        max_var=10.,
        noise_level=0):
    """"
    # modified version of https://github.com/assafshocher/BlindSR_dataset_generator
    # Kai Zhang
    # min_var = 0.175 * sf  # variance of the gaussian kernel will be sampled between min_var and max_var
    # max_var = 2.5 * sf
    """
    # Set random eigen-vals (lambdas) and angle (theta) for COV matrix
    lambda_1 = min_var + np.random.rand() * (max_var - min_var)
    lambda_2 = min_var + np.random.rand() * (max_var - min_var)
    theta = np.random.rand() * np.pi  # random theta
    noise = -noise_level + np.random.rand(*k_size) * noise_level * 2

    # Set COV matrix using Lambdas and Theta
    LAMBDA = np.diag([lambda_1, lambda_2])
    Q = np.array([[np.cos(theta), -np.sin(theta)],
                  [np.sin(theta), np.cos(theta)]])
    SIGMA = Q @ LAMBDA @ Q.T
    INV_SIGMA = np.linalg.inv(SIGMA)[None, None, :, :]

    # Set expectation position (shifting kernel for aligned image)
    MU = k_size // 2 - 0.5 * (scale_factor - 1
                              )  # - 0.5 * (scale_factor - k_size % 2)
    MU = MU[None, None, :, None]

    # Create meshgrid for Gaussian
    [X, Y] = np.meshgrid(range(k_size[0]), range(k_size[1]))
    Z = np.stack([X, Y], 2)[:, :, :, None]

    # Calcualte Gaussian for every pixel of the kernel
    ZZ = Z - MU
    ZZ_t = ZZ.transpose(0, 1, 3, 2)
    raw_kernel = np.exp(-0.5 * np.squeeze(ZZ_t @ INV_SIGMA @ ZZ)) * (1 + noise)

    # shift the kernel so it will be centered
    # raw_kernel_centered = kernel_shift(raw_kernel, scale_factor)

    # Normalize the kernel and return
    # kernel = raw_kernel_centered / np.sum(raw_kernel_centered)
    kernel = raw_kernel / np.sum(raw_kernel)
    return kernel


def fspecial_gaussian(hsize, sigma):
    hsize = [hsize, hsize]
    siz = [(hsize[0] - 1.0) / 2.0, (hsize[1] - 1.0) / 2.0]
    std = sigma
    [x, y] = np.meshgrid(
        np.arange(-siz[1], siz[1] + 1), np.arange(-siz[0], siz[0] + 1))
    arg = -(x * x + y * y) / (2 * std * std)
    h = np.exp(arg)
    h[h < scipy.finfo(float).eps * h.max()] = 0
    sumh = h.sum()
    if sumh != 0:
        h = h / sumh
    return h


def fspecial_laplacian(alpha):
    alpha = max([0, min([alpha, 1])])
    h1 = alpha / (alpha + 1)
    h2 = (1 - alpha) / (alpha + 1)
    h = [[h1, h2, h1], [h2, -4 / (alpha + 1), h2], [h1, h2, h1]]
    h = np.array(h)
    return h


def fspecial(filter_type, *args, **kwargs):
    '''
    python code from:
    https://github.com/ronaldosena/imagens-medicas-2/blob/40171a6c259edec7827a6693a93955de2bd39e76/Aulas/aula_2_-_uniform_filter/matlab_fspecial.py
    '''
    if filter_type == 'gaussian':
        return fspecial_gaussian(*args, **kwargs)
    if filter_type == 'laplacian':
        return fspecial_laplacian(*args, **kwargs)


"""
# --------------------------------------------
# degradation models
# --------------------------------------------
"""


def bicubic_degradation(x, sf=3):
    '''
    Args:
        x: HxWxC image, [0, 1]
        sf: down-scale factor
    Return:
        bicubicly downsampled LR image
    '''
    x = util.imresize_np(x, scale=1 / sf)
    return x


def srmd_degradation(x, k, sf=3):
    ''' blur + bicubic downsampling
    Args:
        x: HxWxC image, [0, 1]
        k: hxw, double
        sf: down-scale factor
    Return:
        downsampled LR image
    Reference:
        @inproceedings{zhang2018learning,
          title={Learning a single convolutional super-resolution network for multiple degradations},
          author={Zhang, Kai and Zuo, Wangmeng and Zhang, Lei},
          booktitle={IEEE Conference on Computer Vision and Pattern Recognition},
          pages={3262--3271},
          year={2018}
        }
    '''
    x = ndimage.filters.convolve(
        x, np.expand_dims(k, axis=2), mode='wrap')  # 'nearest' | 'mirror'
    x = bicubic_degradation(x, sf=sf)
    return x


def dpsr_degradation(x, k, sf=3):
    ''' bicubic downsampling + blur
    Args:
        x: HxWxC image, [0, 1]
        k: hxw, double
        sf: down-scale factor
    Return:
        downsampled LR image
    Reference:
        @inproceedings{zhang2019deep,
          title={Deep Plug-and-Play Super-Resolution for Arbitrary Blur Kernels},
          author={Zhang, Kai and Zuo, Wangmeng and Zhang, Lei},
          booktitle={IEEE Conference on Computer Vision and Pattern Recognition},
          pages={1671--1681},
          year={2019}
        }
    '''
    x = bicubic_degradation(x, sf=sf)
    x = ndimage.filters.convolve(x, np.expand_dims(k, axis=2), mode='wrap')
    return x


def classical_degradation(x, k, sf=3):
    ''' blur + downsampling
    Args:
        x: HxWxC image, [0, 1]/[0, 255]
        k: hxw, double
        sf: down-scale factor
    Return:
        downsampled LR image
    '''
    x = ndimage.filters.convolve(x, np.expand_dims(k, axis=2), mode='wrap')
    # x = filters.correlate(x, np.expand_dims(np.flip(k), axis=2))
    st = 0
    return x[st::sf, st::sf, ...]


def add_sharpening(img, weight=0.5, radius=50, threshold=10):
    """USM sharpening. borrowed from real-ESRGAN
    Input image: I; Blurry image: B.
    1. K = I + weight * (I - B)
    2. Mask = 1 if abs(I - B) > threshold, else: 0
    3. Blur mask:
    4. Out = Mask * K + (1 - Mask) * I
    Args:
        img (Numpy array): Input image, HWC, BGR; float32, [0, 1].
        weight (float): Sharp weight. Default: 1.
        radius (float): Kernel size of Gaussian blur. Default: 50.
        threshold (int):
    """
    if radius % 2 == 0:
        radius += 1
    blur = cv2.GaussianBlur(img, (radius, radius), 0)
    residual = img - blur
    mask = np.abs(residual) * 255 > threshold
    mask = mask.astype('float32')
    soft_mask = cv2.GaussianBlur(mask, (radius, radius), 0)

    K = img + weight * residual
    K = np.clip(K, 0, 1)
    return soft_mask * K + (1 - soft_mask) * img


def add_blur(img, sf=4):
    wd2 = 4.0 + sf
    wd = 2.0 + 0.2 * sf

    wd2 = wd2 / 4
    wd = wd / 4

    if random.random() < 0.5:
        l1 = wd2 * random.random()
        l2 = wd2 * random.random()
        k = anisotropic_Gaussian(
            ksize=random.randint(2, 11) + 3,
            theta=random.random() * np.pi,
            l1=l1,
            l2=l2)
    else:
        k = fspecial('gaussian',
                     random.randint(2, 4) + 3, wd * random.random())
    img = ndimage.filters.convolve(
        img, np.expand_dims(k, axis=2), mode='mirror')

    return img


def add_resize(img, sf=4):
    rnum = np.random.rand()
    if rnum > 0.8:  # up
        sf1 = random.uniform(1, 2)
    elif rnum < 0.7:  # down
        sf1 = random.uniform(0.5 / sf, 1)
    else:
        sf1 = 1.0
    img = cv2.resize(
        img, (int(sf1 * img.shape[1]), int(sf1 * img.shape[0])),
        interpolation=random.choice([1, 2, 3]))
    img = np.clip(img, 0.0, 1.0)

    return img


# def add_Gaussian_noise(img, noise_level1=2, noise_level2=25):
#     noise_level = random.randint(noise_level1, noise_level2)
#     rnum = np.random.rand()
#     if rnum > 0.6:  # add color Gaussian noise
#         img += np.random.normal(0, noise_level / 255.0, img.shape).astype(np.float32)
#     elif rnum < 0.4:  # add grayscale Gaussian noise
#         img += np.random.normal(0, noise_level / 255.0, (*img.shape[:2], 1)).astype(np.float32)
#     else:  # add  noise
#         L = noise_level2 / 255.
#         D = np.diag(np.random.rand(3))
#         U = orth(np.random.rand(3, 3))
#         conv = np.dot(np.dot(np.transpose(U), D), U)
#         img += np.random.multivariate_normal([0, 0, 0], np.abs(L ** 2 * conv), img.shape[:2]).astype(np.float32)
#     img = np.clip(img, 0.0, 1.0)
#     return img


def add_Gaussian_noise(img, noise_level1=2, noise_level2=25):
    noise_level = random.randint(noise_level1, noise_level2)
    rnum = np.random.rand()
    if rnum > 0.6:  # add color Gaussian noise
        img = img + np.random.normal(0, noise_level / 255.0, img.shape).astype(
            np.float32)
    elif rnum < 0.4:  # add grayscale Gaussian noise
        img = img + np.random.normal(0, noise_level / 255.0,
                                     (*img.shape[:2], 1)).astype(np.float32)
    else:  # add  noise
        L = noise_level2 / 255.
        D = np.diag(np.random.rand(3))
        U = orth(np.random.rand(3, 3))
        conv = np.dot(np.dot(np.transpose(U), D), U)
        img = img + np.random.multivariate_normal([0, 0, 0], np.abs(
            L**2 * conv), img.shape[:2]).astype(np.float32)
    img = np.clip(img, 0.0, 1.0)
    return img


def add_speckle_noise(img, noise_level1=2, noise_level2=25):
    noise_level = random.randint(noise_level1, noise_level2)
    img = np.clip(img, 0.0, 1.0)
    rnum = random.random()
    if rnum > 0.6:
        img += img * np.random.normal(0, noise_level / 255.0,
                                      img.shape).astype(np.float32)
    elif rnum < 0.4:
        img += img * np.random.normal(0, noise_level / 255.0,
                                      (*img.shape[:2], 1)).astype(np.float32)
    else:
        L = noise_level2 / 255.
        D = np.diag(np.random.rand(3))
        U = orth(np.random.rand(3, 3))
        conv = np.dot(np.dot(np.transpose(U), D), U)
        img += img * np.random.multivariate_normal(
            [0, 0, 0], np.abs(L**2 * conv), img.shape[:2]).astype(np.float32)
    img = np.clip(img, 0.0, 1.0)
    return img


def add_Poisson_noise(img):
    img = np.clip((img * 255.0).round(), 0, 255) / 255.
    vals = 10**(2 * random.random() + 2.0)  # [2, 4]
    if random.random() < 0.5:
        img = np.random.poisson(img * vals).astype(np.float32) / vals
    else:
        img_gray = np.dot(img[..., :3], [0.299, 0.587, 0.114])
        img_gray = np.clip((img_gray * 255.0).round(), 0, 255) / 255.
        noise_gray = np.random.poisson(img_gray * vals).astype(
            np.float32) / vals - img_gray
        img += noise_gray[:, :, np.newaxis]
    img = np.clip(img, 0.0, 1.0)
    return img


def add_JPEG_noise(img):
    quality_factor = random.randint(80, 95)
    img = cv2.cvtColor(util.single2uint(img), cv2.COLOR_RGB2BGR)
    result, encimg = cv2.imencode(
        '.jpg', img, [int(cv2.IMWRITE_JPEG_QUALITY), quality_factor])
    img = cv2.imdecode(encimg, 1)
    img = cv2.cvtColor(util.uint2single(img), cv2.COLOR_BGR2RGB)
    return img


def random_crop(lq, hq, sf=4, lq_patchsize=64):
    h, w = lq.shape[:2]
    rnd_h = random.randint(0, h - lq_patchsize)
    rnd_w = random.randint(0, w - lq_patchsize)
    lq = lq[rnd_h:rnd_h + lq_patchsize, rnd_w:rnd_w + lq_patchsize, :]

    rnd_h_H, rnd_w_H = int(rnd_h * sf), int(rnd_w * sf)
    hq = hq[rnd_h_H:rnd_h_H + lq_patchsize * sf,
            rnd_w_H:rnd_w_H + lq_patchsize * sf, :]
    return lq, hq


def degradation_bsrgan(img, sf=4, lq_patchsize=72, isp_model=None):
    """
    This is the degradation model of BSRGAN from the paper
    "Designing a Practical Degradation Model for Deep Blind Image Super-Resolution"
    ----------
    img: HXWXC, [0, 1], its size should be large than (lq_patchsizexsf)x(lq_patchsizexsf)
    sf: scale factor
    isp_model: camera ISP model
    Returns
    -------
    img: low-quality patch, size: lq_patchsizeXlq_patchsizeXC, range: [0, 1]
    hq: corresponding high-quality patch, size: (lq_patchsizexsf)X(lq_patchsizexsf)XC, range: [0, 1]
    """
    isp_prob, jpeg_prob, scale2_prob = 0.25, 0.9, 0.25
    sf_ori = sf

    h1, w1 = img.shape[:2]
    img = img.copy()[:w1 - w1 % sf, :h1 - h1 % sf, ...]  # mod crop
    h, w = img.shape[:2]

    if h < lq_patchsize * sf or w < lq_patchsize * sf:
        raise ValueError(f'img size ({h1}X{w1}) is too small!')

    hq = img.copy()

    if sf == 4 and random.random() < scale2_prob:  # downsample1
        if np.random.rand() < 0.5:
            img = cv2.resize(
                img, (int(1 / 2 * img.shape[1]), int(1 / 2 * img.shape[0])),
                interpolation=random.choice([1, 2, 3]))
        else:
            img = util.imresize_np(img, 1 / 2, True)
        img = np.clip(img, 0.0, 1.0)
        sf = 2

    shuffle_order = random.sample(range(7), 7)
    idx1, idx2 = shuffle_order.index(2), shuffle_order.index(3)
    if idx1 > idx2:  # keep downsample3 last
        shuffle_order[idx1], shuffle_order[idx2] = shuffle_order[
            idx2], shuffle_order[idx1]

    for i in shuffle_order:

        if i == 0:
            img = add_blur(img, sf=sf)

        elif i == 1:
            img = add_blur(img, sf=sf)

        elif i == 2:
            a, b = img.shape[1], img.shape[0]
            # downsample2
            if random.random() < 0.75:
                sf1 = random.uniform(1, 2 * sf)
                img = cv2.resize(
                    img,
                    (int(1 / sf1 * img.shape[1]), int(1 / sf1 * img.shape[0])),
                    interpolation=random.choice([1, 2, 3]))
            else:
                k = fspecial('gaussian', 25, random.uniform(0.1, 0.6 * sf))
                k_shifted = shift_pixel(k, sf)
                k_shifted = k_shifted / k_shifted.sum(
                )  # blur with shifted kernel
                img = ndimage.filters.convolve(
                    img, np.expand_dims(k_shifted, axis=2), mode='mirror')
                img = img[0::sf, 0::sf, ...]  # nearest downsampling
            img = np.clip(img, 0.0, 1.0)

        elif i == 3:
            # downsample3
            img = cv2.resize(
                img, (int(1 / sf * a), int(1 / sf * b)),
                interpolation=random.choice([1, 2, 3]))
            img = np.clip(img, 0.0, 1.0)

        elif i == 4:
            # add Gaussian noise
            img = add_Gaussian_noise(img, noise_level1=2, noise_level2=8)

        elif i == 5:
            # add JPEG noise
            if random.random() < jpeg_prob:
                img = add_JPEG_noise(img)

        elif i == 6:
            # add processed camera sensor noise
            if random.random() < isp_prob and isp_model is not None:
                with torch.no_grad():
                    img, hq = isp_model.forward(img.copy(), hq)

    # add final JPEG compression noise
    img = add_JPEG_noise(img)

    # random crop
    img, hq = random_crop(img, hq, sf_ori, lq_patchsize)

    return img, hq


# todo no isp_model?
def degradation_bsrgan_variant(image, sf=4, isp_model=None):
    """
    This is the degradation model of BSRGAN from the paper
    "Designing a Practical Degradation Model for Deep Blind Image Super-Resolution"
    ----------
    sf: scale factor
    isp_model: camera ISP model
    Returns
    -------
    img: low-quality patch, size: lq_patchsizeXlq_patchsizeXC, range: [0, 1]
    hq: corresponding high-quality patch, size: (lq_patchsizexsf)X(lq_patchsizexsf)XC, range: [0, 1]
    """
    image = util.uint2single(image)
    isp_prob, jpeg_prob, scale2_prob = 0.25, 0.9, 0.25
    sf_ori = sf

    h1, w1 = image.shape[:2]
    image = image.copy()[:w1 - w1 % sf, :h1 - h1 % sf, ...]  # mod crop
    h, w = image.shape[:2]

    hq = image.copy()

    if sf == 4 and random.random() < scale2_prob:  # downsample1
        if np.random.rand() < 0.5:
            image = cv2.resize(
                image,
                (int(1 / 2 * image.shape[1]), int(1 / 2 * image.shape[0])),
                interpolation=random.choice([1, 2, 3]))
        else:
            image = util.imresize_np(image, 1 / 2, True)
        image = np.clip(image, 0.0, 1.0)
        sf = 2

    shuffle_order = random.sample(range(7), 7)
    idx1, idx2 = shuffle_order.index(2), shuffle_order.index(3)
    if idx1 > idx2:  # keep downsample3 last
        shuffle_order[idx1], shuffle_order[idx2] = shuffle_order[
            idx2], shuffle_order[idx1]

    for i in shuffle_order:

        if i == 0:
            image = add_blur(image, sf=sf)

        # elif i == 1:
        #     image = add_blur(image, sf=sf)

        if i == 0:
            pass

        elif i == 2:
            a, b = image.shape[1], image.shape[0]
            # downsample2
            if random.random() < 0.8:
                sf1 = random.uniform(1, 2 * sf)
                image = cv2.resize(
                    image, (int(1 / sf1 * image.shape[1]),
                            int(1 / sf1 * image.shape[0])),
                    interpolation=random.choice([1, 2, 3]))
            else:
                k = fspecial('gaussian', 25, random.uniform(0.1, 0.6 * sf))
                k_shifted = shift_pixel(k, sf)
                k_shifted = k_shifted / k_shifted.sum(
                )  # blur with shifted kernel
                image = ndimage.filters.convolve(
                    image, np.expand_dims(k_shifted, axis=2), mode='mirror')
                image = image[0::sf, 0::sf, ...]  # nearest downsampling

            image = np.clip(image, 0.0, 1.0)

        elif i == 3:
            # downsample3
            image = cv2.resize(
                image, (int(1 / sf * a), int(1 / sf * b)),
                interpolation=random.choice([1, 2, 3]))
            image = np.clip(image, 0.0, 1.0)

        elif i == 4:
            # add Gaussian noise
            image = add_Gaussian_noise(image, noise_level1=1, noise_level2=2)

        elif i == 5:
            # add JPEG noise
            if random.random() < jpeg_prob:
                image = add_JPEG_noise(image)
        #
        # elif i == 6:
        #     # add processed camera sensor noise
        #     if random.random() < isp_prob and isp_model is not None:
        #         with torch.no_grad():
        #             img, hq = isp_model.forward(img.copy(), hq)

    # add final JPEG compression noise
    image = add_JPEG_noise(image)
    image = util.single2uint(image)
    example = {'image': image}
    return example


if __name__ == '__main__':
    print('hey')
    img = util.imread_uint('utils/test.png', 3)
    img = img[:448, :448]
    h = img.shape[0] // 4
    print('resizing to', h)
    sf = 4
    deg_fn = partial(degradation_bsrgan_variant, sf=sf)
    for i in range(20):
        print(i)
        img_hq = img
        img_lq = deg_fn(img)['image']
        img_hq, img_lq = util.uint2single(img_hq), util.uint2single(img_lq)
        print(img_lq)
        img_lq_bicubic = albumentations.SmallestMaxSize(
            max_size=h, interpolation=cv2.INTER_CUBIC)(image=img_hq)['image']
        print(img_lq.shape)
        print('bicubic', img_lq_bicubic.shape)
        print(img_hq.shape)
        lq_nearest = cv2.resize(
            util.single2uint(img_lq),
            (int(sf * img_lq.shape[1]), int(sf * img_lq.shape[0])),
            interpolation=0)
        lq_bicubic_nearest = cv2.resize(
            util.single2uint(img_lq_bicubic),
            (int(sf * img_lq.shape[1]), int(sf * img_lq.shape[0])),
            interpolation=0)
        img_concat = np.concatenate(
            [lq_bicubic_nearest, lq_nearest,
             util.single2uint(img_hq)], axis=1)
        util.imsave(img_concat, str(i) + '.png')
