彩色图像直方图和灰度图像直方图的原理是一样的，不同的是彩色图像需要分别计算BGR三个通道。
import cv2 import numpy as np import matplotlib.pyplot as plt img = cv2.imread('Cerasus.JPG', 1) imgInfo = img.shape height = imgInfo[0] width = imgInfo[1] count_b = np.zeros(256, np.float) count_g = np.zeros(256, np.float) count_r = np.zeros(256, np.float) for i in range(height): for j in range(width): (b, g, r) = img[i, j] index_b = int(b) index_g = int(g) index_r = int(r) count_b[index_b] = count_b[index_b] + 1 count_g[index_g] = count_g[index_g] + 1 count_r[index_r] = count_r[index_r] + 1 # 计算每一个通道的概率 total = height * width count_b = count_b / total count_g = count_g / total count_r = count_r / total # 绘图 x = np.linspace(0, 256, 256) y1 = count_b plt.figure() plt.bar( x, y1, 0.9, alpha = 1, color = 'b' ) y2 = count_g plt.figure() plt.bar( x, y2, 0.9, alpha = 1, color = 'g' ) y3 = count_r plt.figure() plt.bar( x, y3, 0.9, alpha = 1, color = 'r' ) plt.show() cv2.waitKey(0)
三个通道直方图如下：
