使用OpenCV直方图均衡时出现问题

我想用 Contrast Limited Adaptive Histogram Equalisation (CLAHE)在 OpenCV

错误

代码

import cv2 as cv
from matplotlib import pyplot as plt

imgG = cv.imread('sample.png')

clahe = cv.createCLAHE(clipLimit=2.0, tileGridSize=(8,8))
imgC  = clahe.apply(imgG)

fig = plt.figure(figsize = (20,20))
ax  = fig.add_subplot(111)
ax.imshow(imgC, cmap='gray')
plt.show()

猜猜为什么会这样