Clahe：Contrast Limited Adaptive Histogram Equalization 对比度受限的自适应直方图均衡化
Clahe的理论解释：
Clahe理论详解1
Clahe理论详解2
1.函数 cv2.createCLAHE
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{cv2.createCLAHE(clipLimit=None, tileGridSize=None)}
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{clipLimit}
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：对比度限制阈值；
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{tileGridSize}
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：用于直方图均衡化的网格大小。输入图像将被分割成大小相等的矩形块。tileGridSize定义行和列中的块数；
2.灰度图
from PIL import Image
import matplotlib.pyplot as plt
import numpy as np
import cv2
test = Image.open('./tupian/test4.png').convert('L')
test = np.uint8(test)
test_hist = cv2.equalizeHist(test)
clahe = cv2.createCLAHE(clipLimit=4, tileGridSize=(10,5))
test_clahe = clahe.apply(test)
plt.figure()
plt.subplot(1,3,1),plt.imshow(test, 'gray')
plt.axis('off'),plt.title('原图')
plt.subplot(1,3,2),plt.imshow(test_hist, 'gray')
plt.axis('off'),plt.title('直方图均衡化')
plt.subplot(1,3,3),plt.imshow(test_clahe, 'gray')
plt.axis('off'),plt.title('Clahe')
plt.show()
3.RGB图
from PIL import Image
import matplotlib.pyplot as plt
import numpy as np
import cv2
img = Image.open('./tupian/test5.jpg').convert('RGB')
img = np.uint8(img)
imgr = img[:,:,0]
imgg = img[:,:,1]
imgb = img[:,:,2]
claher = cv2.createCLAHE(clipLimit=3, tileGridSize=(10,18))
claheg = cv2.createCLAHE(clipLimit=2, tileGridSize=(10,18))
claheb = cv2.createCLAHE(clipLimit=1, tileGridSize=(10,18))
cllr = claher.apply(imgr)
cllg = claheg.apply(imgg)
cllb = claheb.apply(imgb)
rgb_img = np.dstack((cllr,cllg,cllb))
plt.subplot(1,2,1),plt.imshow(img)
plt.title('原图'),plt.axis('off')
plt.subplot(1,2,2),plt.imshow(rgb_img)
plt.title('Clahe'),plt.axis('off')
plt.show()
RGB图实验可见：Clahe具有一定的去雾效果