What did you do?

create an uint16 img and invoke img.transpose(Image.FLIP_LEFT_RIGHT)

What did you expect to happen?

horizontally flip the given PIL Image

What actually happened?

random data overflow

What are your OS, Python and Pillow versions?

• OS: Ubuntu & macOS
• Python: 3.6
• Pillow: 5.1.0 ~ 5.3.0 tested

import numpy as np
from PIL import Image
x = np.zeros((10, 10), dtype=np.uint16)
x[1:4, 2:5] = 1
x[5:8, 5:8] = 2
y = Image.fromarray(x)
assert 2 == np.max(y)
y_ = y.transpose(Image.FLIP_LEFT_RIGHT)
assert 2 == np.max(y_) # error occurred, FLIP_TOP_BOTTOM is okay