Isolated prompt photon purity in p-Pb collisions at $\sqrt{s}=8.16$ TeV. Two purity estimates are shown: One is obtained using the ABCD method, whereas the other is obtained using the template fitting approach. The former is used as the default method in the analysis. The boxes denote the systematic uncertainties associated with the purity determination. Dashed lines indicate a fit of the purity using a Sigmoid function.