How to use NIST test suite for a randomness test of an image in Python?

I have done many tests, namely Histogram, Correlation coefficient, entropy to test the randomness of an image in python.

Now, I would like to apply STS test of NIST for an image to test randomness. I have found a python code in Github, but this code is to test the randomness of a binary string. I don't know how to apply to an image.

Any help will be appreciated.