I want to create a PIL image from a NumPy array. Here is my attempt:
# Create a NumPy array, which has four elements. The top-left should be pure
# red, the top-right should be pure blue, the bottom-left should be pure green,
# and the bottom-right should be yellow.
pixels = np.array([[[255, 0, 0], [0, 255, 0]], [[0, 0, 255], [255, 255, 0]]])
# Create a PIL image from the NumPy array
image = Image.fromarray(pixels, 'RGB')
# Print out the pixel values
print image.getpixel((0, 0))
print image.getpixel((0, 1))
print image.getpixel((1, 0))
print image.getpixel((1, 1))
# Save the image
image.save('image.png')
However, the print out gives the following:
(255, 0, 0)
(0, 0, 0)
(0, 0, 0)
(0, 0, 0)
And the saved image has pure red in the top-left, but all the other pixels are black. Why are these other pixels not retaining the colour I have assigned to them in the NumPy array?
The RGB mode is expecting 8-bit values, so just casting your array should fix the problem:
In [25]: image = Image.fromarray(pixels.astype('uint8'), 'RGB')
...:
...: # Print out the pixel values
...: print image.getpixel((0, 0))
...: print image.getpixel((0, 1))
...: print image.getpixel((1, 0))
...: print image.getpixel((1, 1))
...:
(255, 0, 0)
(0, 0, 255)
(0, 255, 0)
(255, 255, 0)
Your numpy array should be of the form:
[[[248 248 248] # R G B
[248 248 248]
[249 249 249]
...
[ 79 76 45]
[ 79 76 45]
[ 78 75 44]]
[[247 247 247]
[247 247 247]
[248 248 248]
...
[ 80 77 46]
[ 79 76 45]
[ 79 76 45]]
...
[[148 121 92]
[149 122 93]
[153 126 97]
...
[126 117 100]
[126 117 100]
[125 116 99]]]
Assuming you have your numpy array stored in np_arr, here is how to convert it to a pillow Image:
from PIL import Image
import numpy as np
new_im = Image.fromarray(np_arr)
To show the new image, use:
new_im.show()