Array of images in python

Question

I am using numpy and matplotlib to import images in python. I would like to crate a 3d array, such that in the 1th and 2th axis I have pixels values and in the 0th axis I have the image number. So far I got something like this:

from PIL import Image                                                            
import numpy                                                                     
import matplotlib.pyplot as plt                                                  
import glob

imageFolderPath = '/home/B/Pictures/'
imagePath = glob.glob(imageFolderPath+'/*.JPG') 

im_array = numpy.array(Image.open(imagePath[0]).convert('L'), 'f')               
im_array = numpy.expand_dims(im_array, axis=0)                                   

for c in range(1, len(imagePath)):                                               
     im_array_new = numpy.array(Image.open(imagePath[c]).convert('L'), 'f')       
     im_array_new = numpy.expand_dims(im_array_new, axis=0)                       
     im_array = numpy.append(im_array, im_array_new, axis=0)

this work, but it is someway ugly. I don't like the fact that I have to expand the dimension of a 2d Array and then append them together. Is there a more elegant way to do that in python? Possibly without having to preallocate a huge 3d array (n photos, x dimension, y dimension)

Maximilian Peters · Accepted Answer · 2017-07-22 17:41:52Z

4

Instead of a for loop you could make an array out of the list comprehension:

from PIL import Image                                                            
import numpy                                                                     
import glob

imageFolderPath = '/home/B/Pictures/'
imagePath = glob.glob(imageFolderPath + '/*.JPG') 

im_array = numpy.array( [numpy.array(Image.open(img).convert('L'), 'f') for img in imagePath] )

edited Jul 22, 2017 at 17:41

Maximilian Peters

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answered Jan 8, 2015 at 15:29

plonser

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1 Comment

BiA Over a year ago

this is by far more elegant then mine. Thanks

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