python opencv灰度直方图

Python OpenCV中的灰度直方图可以通过以下两种方法计算和绘制：

方法一：

import cv2
import matplotlib.pyplot as plt

# 读取图像
img = cv2.imread('path_to_image', cv2.IMREAD_GRAYSCALE)

# 计算直方图
hist = cv2.calcHist([img], [0], None, [256], [0, 256])

# 绘制直方图
plt.plot(hist)
plt.xlabel('Pixel Value')
plt.ylabel('Frequency')
plt.title('Grayscale Histogram')
plt.show()

方法二：

import cv2
import numpy as np
import matplotlib.pyplot as plt

def calcGrayHist(image):
    # 计算灰度直方图
    h, w = image.shape
    grayHist = np.zeros([256], np.uint64)
    for i in range(h):
        for j in range(w):
            grayHist[image[i][j]] += 1
    return grayHist

# 读取图像
image = cv2.imread('path_to_image', cv2.IMREAD_GRAYSCALE)

# 计算直方图
hist = calcGrayHist(image)

# 绘制直方图
plt.plot(hist)
plt.xlabel('Pixel Value')
plt.ylabel('Frequency')
plt.title('Grayscale Histogram')
plt.show()