What did you do?

I am trying to create a PNG image from a Numpy Array. Before converting the array, I transformed values using multiplication.

What did you expect to happen?

I would expect that the array values used as input correspond 1 to 1 with the output, no matter how they were computed.

What actually happened?

When I multiply my initial array using a vector, the final image has wrong pixel values (lots of zeros). However, if I replace the vector with a scalar the pixel values are correct.

What are your OS, Python and Pillow versions?

• OS: MacOS
• Python: 3.8
• Pillow: 8.0.1

import numpy as np
from PIL import Image

vector = np.ones((5, 5, 3)).astype("uint8") * np.array([3])
scalar = np.ones((5, 5, 3)).astype("uint8") * 3

assert np.array_equal(vector, scalar)

vector_img = Image.fromarray(vector, mode="RGB")
scalar_img = Image.fromarray(scalar, mode="RGB")

assert np.array_equal(np.array(vector_img), np.array(scalar_img))