  The emergence of angle-resolved photoemission spectroscopy (ARPES) made it
possible to observe electronic dispersion directly as a spectral function map.
On the other hand, a spectral function map can be obtained theoretically, for
example, in the LDA+DMFT method. The electronic band on such a map is
characterized not only by its energy position at a given $k$-point, but also by
its width and intensity. To illustrate a way of quantitative comparison of
theoretical spectral functions and ARPES data, spectral functions obtained by
the LDA+DMFT method are chosen. It is shown that the theoretical spectral
functions should take into account a number of experimental features: the
photoionization cross section, the experimental energy and angular resolution,
as well as the effects of the photohole lifetime arising in the process of
photoemission. In this article, we present a robust procedure for taking these
experimental features into account by the example of iron-based
high-temperature superconductors (HTSC) systems: NaFeAs and FeSe on a SrTiO$_3$
substrate.
