How to compute HDR-VDP-2?

[Tx000]

HDR-VDP-2 is used to measure perceived visual quality of the HDR image in the actual luminance domain (with the unit of cd/m^2) instead of the normalized domain. In this work, since the luminance maps are normalized, how to compute HDR-VDP-2?
matlab HDR-VDP-2:
function res = hdrvdp( test, reference, color_encoding, pixels_per_degree, options ).
Which color_encoding did you choose?
Thanks.