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python - 如何解决每当我尝试查找多个图像的平均 RGB 值时发生的这个轴错误

问题描述

我一直在创建一个程序，它将以列表的形式返回存储在文件夹中的所有图像的平均 RGB 值。

我已经编写了代码来查找单个图像的平均 RGB 值，如下所示。

import cv2 
import numpy as np 
myimg2 = cv2.imread('/Users/farzeent.farooqui/Desktop/colors.jpg') 
avg_color = np.array(myimg2).mean(axis=(0,1))
avg_rgb = avg_color[::-1]
print(avg_rgb)

然后我使用 for 循环来获取所有图像的 RGB 值

import cv2  
import numpy as np
import os                      

def test():
    path_of_images = "/Users/farzeent.farooqui/Frames"
    list_of_images = os.listdir(path_of_images)

    for image in list_of_images:

        myimg2 = cv2.imread(os.path.join(path_of_images, image) )
        avg_color = np.array(myimg2).mean(axis=(0,1))
        avg_rgb = avg_color[::-1]
        print(avg_rgb)
test()

但是当我尝试运行程序时，我不断收到以下错误：

---------------------------------------------------------------------------
AxisError                                 Traceback (most recent call last)
<ipython-input-124-fbd55f77ab7c> in <module>
----> 1 test()

 <ipython-input-123-ed7d4e9de700> in test()
     10 
     11         myimg2 = cv2.imread(os.path.join(path_of_images, image) )
 ---> 12         avg_color = np.array(myimg2).mean(axis=(0,1))
     13         avg_rgb = avg_color[::-1]
 14         print(avg_rgb)

~/opt/anaconda3/lib/python3.8/site-packages/numpy/core/_methods.py in _mean(a,         axis, dtype, out, keepdims, where)
    164     is_float16_result = False
    165 
--> 166     rcount = _count_reduce_items(arr, axis, keepdims=keepdims, where=where)
    167     if rcount == 0 if where is True else umr_any(rcount == 0):
    168         warnings.warn("Mean of empty slice.", RuntimeWarning, stacklevel=2)

~/opt/anaconda3/lib/python3.8/site-packages/numpy/core/_methods.py in    _count_reduce_items(arr, axis, keepdims, where)
    73         items = nt.intp(1)
    74         for ax in axis:
---> 75             items *= arr.shape[mu.normalize_axis_index(ax, arr.ndim)]
    76     else:
    77         # TODO: Optimize case when `where` is broadcast along a non-reduction

AxisError: axis 0 is out of bounds for array of dimension 0

标签： pythonnumpy

解决方案

正如@burglarhobbit 在评论中指出的那样，您的目录可能包含非图像文件，这会导致您的代码抛出错误。

下面的代码将帮助您在特定目录中查找具有已知图像文件扩展名的文件。

from os import path, walk

def get_image_files(directory_of_images):
    """
     This function is designed to traverse a directory tree and extract all
     the image names contained in the directory.
    :param directory_of_images: the name of the target directory containing
           the images to be trained on.
    :return: list of images to be processed.
    """
    images_to_process = []
    accepted_extensions = ('.bmp', '.gif', '.jpg', '.jpeg', '.png', '.svg', '.tiff')
    for (dirpath, dirnames, filenames) in walk(directory_of_images):
        for filename in filenames:
            if filename.endswith(accepted_extensions):
                images_to_process.append(path.join(dirpath, filename))
        return images_to_process


list_of_images = get_image_files('/Users/user_name/Python_Projects/scratch_pad')
for image_to_process in list_of_images:
    myimg2 = cv2.imread(image_to_process)
    avg_color = np.array(myimg2).mean(axis=(0, 1))
    avg_rgb = avg_color[::-1]
    print(avg_rgb)
    # output
    [239.08779842 239.08779842 239.08779842]
    [186.64632099 163.64886914 150.54838519]

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