  We present a proof-of-principle determination of the Hubble parameter $H(z)$
from photometric data, obtaining a determination at an effective redshift of
$z=0.75$ ($0.65<z<0.85$) of $H(0.75) =105.0\pm 7.9(stat)\pm 7.3(sys)$ km
s$^{-1}$ Mpc$^{-1}$, with 7.5\% statistical and 7\% systematic (10\% with
statistical and systematics combined in quadrature) accuracy. This is obtained
in a cosmology model-independent fashion, but assuming a linear age-redshift
relation in the relevant redshift range, as such, it can be used to constrain
arbitrary cosmologies as long as $H(z)$ can be considered slowly varying over
redshift. In particular, we have applied a neural network, trained on a
well-studied spectroscopic sample of 140 objects, to the {\tt COSMOS2015}
survey to construct a set of 19 thousand near-passively evolving galaxies and
build an age-redshift relation. The Hubble parameter is given by the derivative
of the red envelope of the age-redshift relation. This is the first time the
Hubble parameter is determined from photometry at $\lesssim 10$\% accuracy.
Accurate $H(z)$ determinations could help shed light on the Hubble tension;
this study shows that photometry, with a reduction of only a factor of two in
the uncertainty, could provide a new perspective on the tension.
