import os
from PIL import Image
import matplotlib.pyplot as plt
import numpy as np
from scipy.misc import imread
filepath ='/home/JPEGImages' # 数据集目录
pathDir = os.listdir(filepath)
R_channel =0
G_channel =0
B_channel =0
for idx in xrange(len(pathDir)):
filename = pathDir[idx]
img = imread(os.path.join(filepath, filename))
R_channel = R_channel + np.sum(img[:,:,0])
G_channel = G_channel + np.sum(img[:,:,1])
B_channel = B_channel + np.sum(img[:,:,2])
num = len(pathDir) *384 * 512 # 这里（384,512）是每幅图片的大小，所有图片尺寸都一样
R_mean = R_channel / num
G_mean = G_channel / num
B_mean = B_channel / num
print("R_mean is %f, G_mean is %f, B_mean is %f" %(R_mean, G_mean, B_mean))
