For an overview of the process of computing the jet faking photon estimate, and to see results obtained for 2016 data, read Jet_Faking_Photon_Estimation.pdf.
To compute the QCD fake ratio, cd to compute_fakeratio and follow the instructions in submit_QCDfake.sh.
To apply the QCD fake ratio to data (in order to estimate the jet faking photon contribution in signal and control regions), cd to apply_fakeratio and follow the instructions in How_to_find_qcdfake_yields.sh.