Mistake: the shape proves reshape worked

“Both results have shape (3, 2, 2), so both are valid CHW images.”

hwc = np.arange(12).reshape(2, 2, 3)
right = hwc.transpose(2, 0, 1)
wrong = hwc.reshape(3, 2, 2)
assert right.shape == wrong.shape
assert right[1, 0, 0] == hwc[0, 0, 1] == 1
assert wrong[1, 0, 0] == 4

Shape checks pass; a channel-value check fails. right[1, 0, 0] is 1, the value that really belongs there — wrong[1, 0, 0] is 4. Use transpose to reorder axes.