def correctCross(raw, factor=2.15):
    """100000 loops, best of 3: 18 us per loop."""
    raw[255:258] = raw[255] / factor
    raw[:, 255:258] = raw[:, 255:256] / factor
    raw[258:261] = raw[260] / factor
    raw[:, 258:261] = raw[:, 260:261] / factor
