read dynamic number of images of same shape into Python NumPy array

Question

I have this code:

image_list = []
for filename in glob.glob('C:\\Users\\Utilizador\\Desktop\\menu\\*.jpg'): 
    im=cv2.imread(filename)
    image_list.append(im)

This creates me a list of images, but I need it to be in an array form with shape (num_of_images, width, height, 3)

All images have the same shape Any ideas? Thanks

yes they have the same shape

Miguel Santos
– Miguel Santos

2018-06-21 10:41:31 +00:00
Commented Jun 21, 2018 at 10:41 — Miguel Santos
– Miguel Santos, Commented Jun 21, 2018 at 10:41

Miguel Santos · Accepted Answer · 2018-06-21 11:41:55Z

1

Since all images have same shape, we can create an empty array and then read each image into that.

In [103]: file_path = 'C:\\Users\\Utilizador\\Desktop\\menu\\*.jpg'
In [104]: num_imgs = len(glob.glob(file_path))
In [105]: width, height, channels = 512, 512, 3

In [106]: batch_arr = np.empty((num_imgs, width, height, channels), dtype=np.uint8)

In [107]: for idx, filename in enumerate(glob.glob(file_path)):
              img = cv2.imread(filename)
              # if img is of different width and height than defined above
              # do some resize and then insert in the array.
              batch_arr[idx] = img

edited Jun 21, 2018 at 11:41

Miguel Santos

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answered Jun 21, 2018 at 10:44

kmario23

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3 Comments

Miguel Santos Over a year ago

That works, but I would like something more dynamic, where the number of images, width, height would not be fixed, like a way to read the images and just append them as an array instead of a list

Miguel Santos Over a year ago

But will it be possible to then edit the images, like resizing them for example inside the array? Or should I do it before I add them to the array?

Miguel Santos Over a year ago

there is an issue, the original image is uint8 format and when I append to the array, it becames float64 and this messes up the image.

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