I've used Pre-Flashing extensively for reducing excessive contrast in color printing. An example would be a Bridal Party - White (blindingly white) gowns on the front steps of a church in bright sunlight.
A "straight" print on the usual color paper (I haven't been all that enamored with Kodak's "graded " RA-4) can give severely washed out, featureless whites and equally featureless blacks.
The idea is to make the paper less sensitive to extreme overexposure and at the same time less sensitive to underxposure... done by analyzing a neutral gray image for color balance and "pre-flashing" the paper for an exposure of 10% - 20% of the final amount, e.g., if the indicated exposure time was 30 seconds, the "pre-flash" time would be 3 to 6 seconds.
The paper is then "removed" - the subject negative analyzed again for color balance and exposure time and the paper is re-exposed for the remaining 80% - 90% or 24 to 27 seconds.
In practice it is much easier to do than to explain.
Both whites and blacks (shadow areas - you can see eyes again) will then improve in detail and texture.