How can I write a binary array as an image in Python?

Question

I have an array of binary numbers in Python:

data = [0, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 1...]

I would like to take this data out and save it as a bitmap, with a '0' corresponding to white and a '1' corresponding to black. I know that there are 2500 numbers in the array, corresponding to a 50x50 bitmap. I've downloaded and installed PIL, but I'm not sure how to use it for this purpose. How can I convert this array into the corresponding image?

Answer 1

You can use Image.new with 1 mode and put each integer as pixel in your initial image:

>>> from PIL import Image
>>> import random

>>> data = [random.choice((0, 1)) for _ in range(2500)]
>>> data[:] = [data[i:i + 50] for i in range(0, 2500, 50)]
>>> print data
[[0, 1, 0, 0, 1, ...], [0, 1, 1, 0, 1, ...], [1, 1, 0, 1, ...], ...]

>>> img = Image.new('1', (50, 50))
>>> pixels = img.load()

>>> for i in range(img.size[0]):
...    for j in range(img.size[1]):
...        pixels[i, j] = data[i][j]

>>> img.show()
>>> img.save('/tmp/image.bmp')

Answer 2

The numpy and matplotlib way of doing it would be:

import matplotlib.pyplot as plt
import matplotlib.cm as cm
import numpy as np
plt.imsave('filename.png', np.array(data).reshape(50,50), cmap=cm.gray)

See this