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import cv2
import numpy as np
import torch
from torch.nn import functional as F
def filter2D(img, kernel):
"""PyTorch version of cv2.filter2D
Args:
img (Tensor): (b, c, h, w)
kernel (Tensor): (b, k, k)
"""
k = kernel.size(-1)
b, c, h, w = img.size()
if k % 2 == 1:
img = F.pad(img, (k // 2, k // 2, k // 2, k // 2), mode='reflect')
else:
raise ValueError('Wrong kernel size')
ph, pw = img.size()[-2:]
if kernel.size(0) == 1:
# apply the same kernel to all batch images
img = img.view(b * c, 1, ph, pw)
kernel = kernel.view(1, 1, k, k)
return F.conv2d(img, kernel, padding=0).view(b, c, h, w)
else:
img = img.view(1, b * c, ph, pw)
kernel = kernel.view(b, 1, k, k).repeat(1, c, 1, 1).view(b * c, 1, k, k)
return F.conv2d(img, kernel, groups=b * c).view(b, c, h, w)
def usm_sharp(img, weight=0.5, radius=50, threshold=10):
"""USM sharpening.
Input image: I; Blurry image: B.
1. sharp = I + weight * (I - B)
2. Mask = 1 if abs(I - B) > threshold, else: 0
3. Blur mask:
4. Out = Mask * sharp + (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)
sharp = img + weight * residual
sharp = np.clip(sharp, 0, 1)
return soft_mask * sharp + (1 - soft_mask) * img
class USMSharp(torch.nn.Module):
def __init__(self, radius=50, sigma=0):
super(USMSharp, self).__init__()
if radius % 2 == 0:
radius += 1
self.radius = radius
kernel = cv2.getGaussianKernel(radius, sigma)
kernel = torch.FloatTensor(np.dot(kernel, kernel.transpose())).unsqueeze_(0)
self.register_buffer('kernel', kernel)
def forward(self, img, weight=0.5, threshold=10):
blur = filter2D(img, self.kernel)
residual = img - blur
mask = torch.abs(residual) * 255 > threshold
mask = mask.float()
soft_mask = filter2D(mask, self.kernel)
sharp = img + weight * residual
sharp = torch.clip(sharp, 0, 1)
return soft_mask * sharp + (1 - soft_mask) * img
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