I'm working with some MODIS satellite imagery. MODIS data includes a
quality flag mask. For the particular dataset I'm working with, this is
a two dimensional unsigned 16 bit integer array. The quality flags are
stored as one or more bits in each integer value:

Bits are numbered from 0 (least significant bit)
       Bit     Long name       Key
       0-1     MODLAND_QA
                               00=VI produced, good quality
                               01=VI produced, but check other QA
                               10=Pixel produced, but most probably
cloudy
                               11=Pixel not produced due to other
reasons
                                  than clouds
       2-5     VI usefulness
                               0000=Highest quality
                               0001=Lower quality
                               0010=Decreasing quality
                               0100=Decreasing quality
                               1000=Decreasing quality
                               1001=Decreasing quality
                               1010=Decreasing quality
                               1100=Lowest quality
                               1101=Quality so low that it is not
useful
                               1110=L1B data faulty
                               1111=Not useful for any other reason/not
                                    processed
       ...<SNIP>...
       15      Possible shadow
                               0=No
                               1=Yes


Some typical values are:
arr=numpy.array([51199,37013,36885,36889,34841,2062,34837,2061,35033,349
61,2185,37013,36885,2185,4109,4233], dtype=numpy.uint16)

How would I extract groups of/individual bit values from such an array?