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import cv2
import math
import numpy as np
import random
# -------------------------------------------------------------------- #
# --------------------------- blur kernels --------------------------- #
# -------------------------------------------------------------------- #
def sigma_matrix2(sig_x, sig_y, theta):
"""Calculate the rotated sigma matrix (two dimensional matrix).
Args:
sig_x (float):
sig_y (float):
theta (float): Radian measurement.
Returns:
ndarray: Rotated sigma matrix.
"""
D = np.array([[sig_x**2, 0], [0, sig_y**2]])
U = np.array([[np.cos(theta), -np.sin(theta)], [np.sin(theta), np.cos(theta)]])
return np.dot(U, np.dot(D, U.T))
def mesh_grid(kernel_size):
"""Generate the mesh grid, centering at zero.
Args:
kernel_size (int):
Returns:
xy (ndarray): with the shape (kernel_size, kernel_size, 2)
xx (ndarray): with the shape (kernel_size, kernel_size)
yy (ndarray): with the shape (kernel_size, kernel_size)
"""
ax = np.arange(-kernel_size // 2 + 1., kernel_size // 2 + 1.)
xx, yy = np.meshgrid(ax, ax)
xy = np.hstack((xx.reshape((kernel_size * kernel_size, 1)), yy.reshape(kernel_size * kernel_size,
1))).reshape(kernel_size, kernel_size, 2)
return xy, xx, yy
def pdf2(sigma_matrix, grid):
"""Calculate PDF of the bivariate Gaussian distribution.
Args:
sigma_matrix (ndarray): with the shape (2, 2)
grid (ndarray): generated by :func:`mesh_grid`,
with the shape (K, K, 2), K is the kernel size.
Returns:
kernel (ndarrray): un-normalized kernel.
"""
inverse_sigma = np.linalg.inv(sigma_matrix)
kernel = np.exp(-0.5 * np.sum(np.dot(grid, inverse_sigma) * grid, 2))
return kernel
def mass_center_shift(kernel_size, kernel):
"""Calculate the shift of the mass center of a kenrel.
Args:
kernel_size (int):
kernel (ndarray): normalized kernel.
Returns:
delta_h (float):
delta_w (float):
"""
ax = np.arange(-kernel_size // 2 + 1., kernel_size // 2 + 1.)
col_sum, row_sum = np.sum(kernel, axis=0), np.sum(kernel, axis=1)
delta_h = np.dot(row_sum, ax)
delta_w = np.dot(col_sum, ax)
return delta_h, delta_w
def bivariate_anisotropic_Gaussian(kernel_size, sig_x, sig_y, theta, grid=None):
"""Generate a bivariate anisotropic Gaussian kernel.
Args:
kernel_size (int):
sig_x (float):
sig_y (float):
theta (float): Radian measurement.
grid (ndarray, optional): generated by :func:`mesh_grid`,
with the shape (K, K, 2), K is the kernel size. Default: None
Returns:
kernel (ndarray): normalized kernel.
"""
if grid is None:
grid, _, _ = mesh_grid(kernel_size)
sigma_matrix = sigma_matrix2(sig_x, sig_y, theta)
kernel = pdf2(sigma_matrix, grid)
kernel = kernel / np.sum(kernel)
return kernel
def bivariate_isotropic_Gaussian(kernel_size, sig, grid=None):
"""Generate a bivariate isotropic Gaussian kernel.
Args:
kernel_size (int):
sig (float):
grid (ndarray, optional): generated by :func:`mesh_grid`,
with the shape (K, K, 2), K is the kernel size. Default: None
Returns:
kernel (ndarray): normalized kernel.
"""
if grid is None:
grid, _, _ = mesh_grid(kernel_size)
sigma_matrix = np.array([[sig**2, 0], [0, sig**2]])
kernel = pdf2(sigma_matrix, grid)
kernel = kernel / np.sum(kernel)
return kernel
def random_bivariate_anisotropic_Gaussian(kernel_size,
sigma_x_range,
sigma_y_range,
rotation_range,
noise_range=None,
strict=False):
"""Randomly generate bivariate anisotropic Gaussian kernels.
Args:
kernel_size (int):
sigma_x_range (tuple): [0.6, 5]
sigma_y_range (tuple): [0.6, 5]
rotation range (tuple): [-math.pi, math.pi]
noise_range(tuple, optional): multiplicative kernel noise,
[0.75, 1.25]. Default: None
Returns:
kernel (ndarray):
"""
assert kernel_size % 2 == 1, 'Kernel size must be an odd number.'
assert sigma_x_range[0] < sigma_x_range[1], 'Wrong sigma_x_range.'
assert sigma_y_range[0] < sigma_y_range[1], 'Wrong sigma_y_range.'
assert rotation_range[0] < rotation_range[1], 'Wrong rotation_range.'
sigma_x = np.random.uniform(sigma_x_range[0], sigma_x_range[1])
sigma_y = np.random.uniform(sigma_y_range[0], sigma_y_range[1])
if strict:
sigma_max = np.max([sigma_x, sigma_y])
sigma_min = np.min([sigma_x, sigma_y])
sigma_x, sigma_y = sigma_max, sigma_min
rotation = np.random.uniform(rotation_range[0], rotation_range[1])
kernel = bivariate_anisotropic_Gaussian(kernel_size, sigma_x, sigma_y, rotation)
# add multiplicative noise
if noise_range is not None:
assert noise_range[0] < noise_range[1], 'Wrong noise range.'
noise = np.random.uniform(noise_range[0], noise_range[1], size=kernel.shape)
kernel = kernel * noise
kernel = kernel / np.sum(kernel)
if strict:
return kernel, sigma_x, sigma_y, rotation
else:
return kernel
def random_bivariate_isotropic_Gaussian(kernel_size, sigma_range, noise_range=None, strict=False):
"""Randomly generate bivariate isotropic Gaussian kernels.
Args:
kernel_size (int):
sigma_range (tuple): [0.6, 5]
noise_range(tuple, optional): multiplicative kernel noise,
[0.75, 1.25]. Default: None
Returns:
kernel (ndarray):
"""
assert kernel_size % 2 == 1, 'Kernel size must be an odd number.'
assert sigma_range[0] < sigma_range[1], 'Wrong sigma_x_range.'
sigma = np.random.uniform(sigma_range[0], sigma_range[1])
kernel = bivariate_isotropic_Gaussian(kernel_size, sigma)
# add multiplicative noise
if noise_range is not None:
assert noise_range[0] < noise_range[1], 'Wrong noise range.'
noise = np.random.uniform(noise_range[0], noise_range[1], size=kernel.shape)
kernel = kernel * noise
kernel = kernel / np.sum(kernel)
if strict:
return kernel, sigma
else:
return kernel
def random_mixed_kernels(kernel_list,
kernel_prob,
kernel_size=21,
sigma_x_range=[0.6, 5],
sigma_y_range=[0.6, 5],
rotation_range=[-math.pi, math.pi],
beta_range=[0.5, 8],
noise_range=None):
"""Randomly generate mixed kernels.
Args:
kernel_list (tuple): a list name of kenrel types,
support ['iso', 'aniso']
kernel_prob (tuple): corresponding kernel probability for each
kernel type
kernel_size (int):
sigma_x_range (tuple): [0.6, 5]
sigma_y_range (tuple): [0.6, 5]
rotation range (tuple): [-math.pi, math.pi]
beta_range (tuple): [0.5, 8]
noise_range(tuple, optional): multiplicative kernel noise,
[0.75, 1.25]. Default: None
Returns:
kernel (ndarray):
"""
kernel_type = random.choices(kernel_list, kernel_prob)[0]
if kernel_type == 'iso':
kernel = random_bivariate_isotropic_Gaussian(kernel_size, sigma_x_range, noise_range=noise_range)
elif kernel_type == 'aniso':
kernel = random_bivariate_anisotropic_Gaussian(
kernel_size, sigma_x_range, sigma_y_range, rotation_range, noise_range=noise_range)
# add multiplicative noise
if noise_range is not None:
assert noise_range[0] < noise_range[1], 'Wrong noise range.'
noise = np.random.uniform(noise_range[0], noise_range[1], size=kernel.shape)
kernel = kernel * noise
kernel = kernel / np.sum(kernel)
return kernel
# ------------------------------------------------------------- #
# --------------------------- noise --------------------------- #
# ------------------------------------------------------------- #
# ----------------------- Gaussian Noise ----------------------- #
def generate_gaussian_noise(img, sigma=10, gray_noise=False):
"""Generate Gaussian noise.
Args:
img (Numpy array): Input image, shape (h, w, c), range [0, 1], float32.
sigma (float): Noise scale (measured in range 255). Default: 10.
Returns:
(Numpy array): Returned noisy image, shape (h, w, c), range[0, 1],
float32.
"""
noise = np.float32(np.random.randn(*(img.shape))) * sigma / 255.
if gray_noise:
noise = np.float32(np.random.randn(*(img.shape[0:2]))) * sigma / 255.
noise = np.expand_dims(noise, axis=2).repeat(3, axis=2)
else:
noise = np.float32(np.random.randn(*(img.shape))) * sigma / 255.
return noise
def add_gaussian_noise(img, sigma=10, clip=True, rounds=False, gray_noise=False):
"""Add Gaussian noise.
Args:
img (Numpy array): Input image, shape (h, w, c), range [0, 1], float32.
sigma (float): Noise scale (measured in range 255). Default: 10.
Returns:
(Numpy array): Returned noisy image, shape (h, w, c), range[0, 1],
float32.
"""
noise = generate_gaussian_noise(img, sigma, gray_noise)
out = img + noise
if clip and rounds:
out = np.clip((out * 255.0).round(), 0, 255) / 255.
elif clip:
out = np.clip(out, 0, 1)
elif rounds:
out = (out * 255.0).round() / 255.
return out
# ----------------------- Random Gaussian Noise ----------------------- #
def random_generate_gaussian_noise(img, sigma_range=(0, 10), gray_prob=0):
sigma = np.random.uniform(sigma_range[0], sigma_range[1])
if np.random.uniform() < gray_prob:
gray_noise = True
else:
gray_noise = False
return generate_gaussian_noise(img, sigma, gray_noise)
def random_add_gaussian_noise(img, sigma_range=(0, 1.0), gray_prob=0, clip=True, rounds=False):
noise = random_generate_gaussian_noise(img, sigma_range, gray_prob)
out = img + noise
if clip and rounds:
out = np.clip((out * 255.0).round(), 0, 255) / 255.
elif clip:
out = np.clip(out, 0, 1)
elif rounds:
out = (out * 255.0).round() / 255.
return out
# ------------------------------------------------------------------------ #
# --------------------------- JPEG compression --------------------------- #
# ------------------------------------------------------------------------ #
def add_jpg_compression(img, quality=90):
"""Add JPG compression artifacts.
Args:
img (Numpy array): Input image, shape (h, w, c), range [0, 1], float32.
quality (float): JPG compression quality. 0 for lowest quality, 100 for
best quality. Default: 90.
Returns:
(Numpy array): Returned image after JPG, shape (h, w, c), range[0, 1],
float32.
"""
img = np.clip(img, 0, 1)
encode_param = [int(cv2.IMWRITE_JPEG_QUALITY), quality]
_, encimg = cv2.imencode('.jpg', img * 255., encode_param)
img = np.float32(cv2.imdecode(encimg, 1)) / 255.
return img
def random_add_jpg_compression(img, quality_range=(90, 100)):
"""Randomly add JPG compression artifacts.
Args:
img (Numpy array): Input image, shape (h, w, c), range [0, 1], float32.
quality_range (tuple[float] | list[float]): JPG compression quality
range. 0 for lowest quality, 100 for best quality.
Default: (90, 100).
Returns:
(Numpy array): Returned image after JPG, shape (h, w, c), range[0, 1],
float32.
"""
quality = np.random.uniform(quality_range[0], quality_range[1])
return add_jpg_compression(img, quality)
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