Importing PNG files into Numpy

Question

I have about 200 grayscale PNG images stored within a directory like this   1 png 2 png 3 png         200 png   I want to import all the PNG images as NumPy arrays  How can I do this

User · Answer

I like the build-in pathlib libary because of quick options like directory= Path.cwd() Together with opencv it's quite easy to read pngs to numpy arrays. In this example you can even check the prefix of the image.

from pathlib import Path
import cv2
prefix = "p00"
suffix = ".png"
directory= Path.cwd()
file_names= [subp.name for subp in directory.rglob('*') if  (prefix in subp.name) & (suffix == subp.suffix)]
file_names.sort()
print(file_names)

all_frames= []
for file_name in file_names:
    file_path = str(directory / file_name)
    frame=cv2.imread(file_path)
    all_frames.append(frame)
print(type(all_frames[0]))
print(all_frames[0] [1][1])

Output:

['p000.png', 'p001.png', 'p002.png', 'p003.png', 'p004.png', 'p005.png', 'p006.png', 'p007.png', 'p008.png', 'p009.png']
<class 'numpy.ndarray'>
[255 255 255]

User · Answer

Using just scipy  glob and having PIL installed  pip install pillow  you can use scipy s imread method   from scipy import misc import glob  for image path in glob glob   home adam   png        image   misc imread image path      print image shape     print image dtype   UPDATE  According to the doc  scipy misc imread is deprecated starting SciPy 1 0 0  and will be removed in 1 2 0  Consider using imageio imread instead  See the answer by Charles

User · Answer

This can also be done with the Image class of the PIL library   from PIL import Image import numpy as np  im frame   Image open path to file    file png   np frame   np array im frame getdata      Note  The  getdata   might not be needed - np array im frame  should also work

User · Answer

Using a  very  commonly used package is prefered   import matplotlib pyplot as plt im   plt imread  image png

User · Answer

I changed a bit and it worked like this  dumped into one single array  provided all the images are of same dimensions   png      for image path in glob glob    train   png        png append misc imread image path        im   np asarray png   print  Importing done      im shape

User · Answer

If you are loading images  you are likely going to be working with one or both of matplotlib and opencv to manipulate and view the images   For this reason  I tend to use their image readers and append those to lists  from which I make a NumPy array   import os import matplotlib pyplot as plt import cv2 import numpy as np    Get the file paths im files   os listdir  path to files       imagine we only want to load PNG files  or JPEG or whatever     EXTENSION     png     Load using matplotlib images plt    plt imread f  for f in im files if f endswith EXTENSION     convert your lists into a numpy array of size  N  H  W  C  images   np array images plt     Load using opencv images cv    cv2 imread f  for f in im files if f endswith EXTENSION     convert your lists into a numpy array of size  N  C  H  W  images   np array images cv    The only difference to be aware of is the following    opencv loads channels first matplotlib loads channels last    So a single image that is 256 256 in size would produce matrices of size  3  256  256  with opencv and  256  256  3  using matplotlib

User · Answer

According to the doc  scipy misc imread is deprecated starting SciPy 1 0 0  and will be removed in 1 2 0  Consider using imageio imread instead  Example  import imageio  im   imageio imread  my image png   print im shape   You can also use imageio to load from fancy sources  im   imageio imread  http   upload wikimedia org wikipedia commons d de Wikipedia Logo 1 0 png    Edit  To load all of the   png files in a specific folder  you could use the glob package  import imageio import glob  for im path in glob glob  quot path to folder   png quot         im   imageio imread im path       print im shape         do whatever with the image here

[python] Importing PNG files into Numpy?

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