计算图像数据集的RGB均值

最近在跑代码的时候，需要用到RGB三个通道上的均值，如下图所示：

写了一个程序，如下：

import os
import cv2
import random
import numpy as np

#数据集的位置
dataset_dir = 'data'

# 验证集图像数量
_NUM_VALIDATION = 1000

# 随机种子
_RANDOM_SEED = 0

def _get_filenames_and_classes(dataset_dir):
  """Returns a list of filenames and inferred class names.

  Args:
	dataset_dir:A directory containing a set of different datasets.Each dataset
	contains a set of subdirectories representing class names.Each subdirectory
	should contain PNG or JPG encoded images.
  Returns:
    A list of image file paths, relative to `dataset_dir` and the list of
    subdirectories, representing class names.
  """
  flower_root = os.path.join(dataset_dir, 'Stripe')
  directories = []
  class_names = []
  for filename in os.listdir(flower_root):
    path = os.path.join(flower_root, filename)
    if os.path.isdir(path):
      directories.append(path)
      class_names.append(filename)

  photo_filenames = []
  for directory in directories:
    for filename in os.listdir(directory):
      path = os.path.join(directory, filename)
      photo_filenames.append(path)
      # Divide into train and test:
  random.seed(_RANDOM_SEED)
  random.shuffle(photo_filenames)
  training_filenames = photo_filenames[_NUM_VALIDATION:]
  #validation_filenames = photo_filenames[:_NUM_VALIDATION]

  return training_filenames

def compute(file_names):
    per_image_Rmean = []
    per_image_Gmean = []
    per_image_Bmean = []
    for file_name in file_names:
        img = cv2.imread(file_name, 1)
        per_image_Rmean.append(np.mean(img[:,:,0]))
        per_image_Gmean.append(np.mean(img[:,:,1]))
        per_image_Bmean.append(np.mean(img[:,:,2]))
    R_mean = np.mean(per_image_Rmean)
    G_mean = np.mean(per_image_Gmean)
    B_mean = np.mean(per_image_Bmean)
    return R_mean, G_mean, B_mean

if __name__ == '__main__':

    photo_filenames = _get_filenames_and_classes(dataset_dir)

    R, G, B= compute(photo_filenames)
    print(R, G ,B)

注释：

目录结构如下所示：

data（放数据集的地方）
        cifar10（数据集）
            airplane
            .....

        Stripe（数据集）
            defect
            normal