My raw data stored on the harddisk is tabular dat file. For example
1    2
3    4

Then I import the data using pandas, thus, img is the panda dataframe. img.values convert this dataframe to normal array:
array([[8.8635123e-01, 5.0047553e-01, 6.9067048e-01, ..., 6.9067048e-01,
         5.0047553e-01, 8.8635123e-01],
        [3.1736772e-01, 4.9979461e-01, 4.5827276e-01, ..., 4.5827276e-01,
         4.9979461e-01, 3.1736772e-01],
        [3.1614803e-01, 4.9785078e-01, 4.5332954e-01, ..., 4.5332954e-01,
         4.9785078e-01, 3.1614803e-01],
        ...,
        [6.4057958e-18, 6.8499766e-18, 1.3891328e-17, ..., 1.1393926e-17,
         2.4889349e-17, 7.0346043e-18],
        [1.1750645e-18, 5.4330497e-18, 2.7927236e-18, ..., 7.4773645e-18,
         1.7836283e-17, 5.2071868e-18],
        [1.0609590e-18, 1.1636564e-18, 2.5262159e-18, ..., 4.1869932e-18,
         1.3754568e-17, 4.4672030e-18]])