python - 总结所有图像的平均像素值 : TypeError: 'numpy.float64' object is not iterable

Question

我必须根据像素值设置阈值才能删除文件夹中的某些图像，并且我需要知道像素值的标准偏差。因此，我需要总结所有平均像素值。

以下是我尝试过的

以下代码演示了 np.mean() 的输出如何

import os,glob
from PIL import Image
from skimage import io
import numpy as np
from statistics import stdev 

path = "/Users/Xin/Desktop/SVM-Image-Classification-master/test"
# Delete images with the low pixel value
for filename in os.listdir(path):
    images = Image.open(os.path.join(path,filename))  
    print(np.mean(images))
    #if np.mean(images) < 20:
        #os.remove(os.path.join(path, filename))
#print(len(os.listdir(path)))

输出如下，值在0~255之间。值越小，图像越黑。

12.685516357421875
14.462142944335938
12.24658203125
9.507644653320312
18.701019287109375
10.004150390625
18.128433227539062
12.625930786132812

以下代码是我尝试过的

path = "/Users/Xin/Desktop/SVM-Image-Classification-master/test"
# Delete images with the low pixel value
for filename in os.listdir(path):
    images = Image.open(os.path.join(path,filename))  
    L = list[round(np.mean(images),2)]
    totalvalue = sum(L)
    print(totalvalue)
    #if np.mean(images) < 20:
        #os.remove(os.path.join(path, filename))
#print(len(os.listdir(path)))

错误提示如下

TypeError: list indices must be integers or slices, not numpy.float64

有人可以帮我吗？非常感谢!

Answer 1

此函数可以代替标准差。

def function(image):
    (R, G, B)= function_for_rgb(image)
    std_dev = statistics.stdev([R, G, B]) #standard deviation
    return  round(std_dev,2)