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 cv2import numpy as npimport matplotlib.pyplot as pltimg = cv2.imread('Cerasus.JPG', 1)imgInfo = img.shapeheight = 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] + 1count_g[index_g] = count_g[index_g] + 1count_r[index_r] = count_r[index_r] + 1# 计算每一个通道的概率total = height * widthcount_b = count_b / totalcount_g = count_g / totalcount_r = count_r / total# 绘图x = np.linspace(0, 256, 256)y1 = count_bplt.figure()plt.bar( x, y1, 0.9, alpha = 1, color = 'b' )y2 = count_gplt.figure()plt.bar( x, y2, 0.9, alpha = 1, color = 'g' )y3 = count_rplt.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：
