print(img.permute(0, 3, 1, 2)[0, 0])
# tensor([[0, 3],
#         [6, 9]])            ← the red value of each of the 4 pixels ✅

print(img.reshape(1, 3, 2, 2)[0, 0])
# tensor([[0, 1],
#         [2, 3]])            ← pixel 0's R, G, B and then pixel 1's R ❌