How to read image from numpy array into PIL Image?

Question

I am trying to read an image from a numpy array using PIL, by doing the following:

from PIL import Image
import numpy as np
#img is a np array with shape (3,256,256)
Image.fromarray(img)

and am getting the following error:

File "...Image.py", line 2155, in fromarray
    raise TypeError("Cannot handle this data type")

I think this is because fromarray expects the shape to be (height, width, num_channels) however the array I have is in the shape (num_channels, height, width) as it is stored in this was in an lmdb database.

How can I reshape the Image so that it is compatible with Image.fromarray?

maybe try `Image.fromarray(np.uint8(img))` – Ryan May 20 '15 at 10:08 — Ryan, May 20 '15 at 10:08
The type of array is uint8, the problem is in the shape – Aly May 20 '15 at 10:11 — Aly, May 20 '15 at 10:11

score 15 · Accepted Answer · answered May 20 '15 at 10:21

15

You don't need to reshape. This is what rollaxis is for:

Image.fromarray(np.rollaxis(img, 0,3))

answered May 20 '15 at 10:21

Lanting

3,060
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28

This. A [C, H, W] array will be rolled to [H, W, C]. Note that it will work only when len(shape) == 3 – Jongwook Choi Aug 29 '23 at 19:54

score 5 · Answer 2 · answered May 20 '15 at 10:19

5

Try

img = np.reshape(256, 256, 3)
Image.fromarray(img)

answered May 20 '15 at 10:19

Ryan

3,555
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score 1 · Answer 3 · answered Dec 24 '20 at 00:44

Defining the datatype of the numpy array to np.uint8 fixed it for me.

>>> img = np.full((256, 256), 3)
>>> Image.fromarray(img)
...
line 2753, in fromarray
raise TypeError("Cannot handle this data type: %s, %s" % typekey) from e
TypeError: Cannot handle this data type: (1, 1), <i8

So defining the array with the proper datatype:

>>> img = np.full((256, 256), 3, dtype=np.uint8)
>>> Image.fromarray(img)
<PIL.Image.Image image mode=L size=256x256 at 0x7F346EA31130>

creates the Image object successfully

Or you could simply modify the existing numpy array:

img = img.astype(np.uint8)

How to read image from numpy array into PIL Image?

3 Answers3

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