Issue
Playing with PIL (and numpy) for the first time ever. I was trying to generate a black and white checkerboard image through mode='1', but it doesn't work.
from PIL import Image
import numpy as np
if __name__ == '__main__':
g = np.asarray(dtype=np.dtype('uint8'), a=[
[0, 1, 0, 1, 0, 1, 0, 1, ],
[1, 0, 1, 0, 1, 0, 1, 0, ],
[0, 1, 0, 1, 0, 1, 0, 1, ],
[1, 0, 1, 0, 1, 0, 1, 0, ],
[0, 1, 0, 1, 0, 1, 0, 1, ],
[1, 0, 1, 0, 1, 0, 1, 0, ],
[0, 1, 0, 1, 0, 1, 0, 1, ],
[1, 0, 1, 0, 1, 0, 1, 0, ],
])
print(g)
i = Image.fromarray(g, mode='1')
i.save('checker.png')
Sorry browser is probably going to try to interpolate this, but it is an 8x8 PNG.
What am I missing?
Relevant PIL docs: https://pillow.readthedocs.org/handbook/concepts.html#concept-modes
$ pip freeze
numpy==1.9.2
Pillow==2.9.0
wheel==0.24.0
Solution
There seem to be issues when using mode 1
with numpy arrays. As a workaround you could use mode L
and convert to mode 1
before saving. The below snippet produces the expected checkerboard.
from PIL import Image
import numpy as np
if __name__ == '__main__':
g = np.asarray(dtype=np.dtype('uint8'), a=[
[0, 255, 0, 255, 0, 255, 0, 255],
[255, 0, 255, 0, 255, 0, 255, 0],
[0, 255, 0, 255, 0, 255, 0, 255],
[255, 0, 255, 0, 255, 0, 255, 0],
[0, 255, 0, 255, 0, 255, 0, 255],
[255, 0, 255, 0, 255, 0, 255, 0],
[0, 255, 0, 255, 0, 255, 0, 255],
[255, 0, 255, 0, 255, 0, 255, 0]
])
print(g)
i = Image.fromarray(g, mode='L').convert('1')
i.save('checker.png')
Answered By - hennes
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