How did researchers significantly increase the galaxy count estimate based on HUDF data?

Answer

By modeling the contribution of fainter galaxies too dim for Hubble to resolve individually

The revision involved using light-gathering statistics from the HUDF data to model what the fainter galaxies, which Hubble could not individually resolve, would contribute to the total population.

How did researchers significantly increase the galaxy count estimate based on HUDF data?
galaxiesastronomyuniversecosmosestimation