Python: reading 12-bit binary files

Question

I am trying to read 12-bit binary files containing images (a video) using Python 3.

To read a similar file but encoded in 16 bits, the following works very well:

Answer 1

Found @cyrilgaudefroy answer useful. However, initially, it did not work on my 12-bit packed binary image data. Found out that the packing is a bit different in this particular case. The "middle" byte contained the least significant nibbles. Bytes 1 and 3 of the triplet are the most significant 8 bits of the twelve. Hence modified @cyrilgaudefroy answer to:

def read_uint12(data_chunk):
    data = np.frombuffer(data_chunk, dtype=np.uint8)
    fst_uint8, mid_uint8, lst_uint8 = np.reshape(data, (data.shape[0] // 3, 3)).astype(np.uint16).T
    fst_uint12 = (fst_uint8 << 4) + (mid_uint8 >> 4)
    snd_uint12 = (lst_uint8 << 4) + (np.bitwise_and(15, mid_uint8))
    return np.reshape(np.concatenate((fst_uint12[:, None], snd_uint12[:, None]), axis=1), 2 * fst_uint12.shape[0])