Flash photography was a thing then, this photograph looks like a Flash is illuminating it.
> through the 1920s, flash photography normally meant a professional photographer sprinkling powder into the trough of a T-shaped flash lamp, holding it aloft, then triggering a brief and (usually) harmless bit of pyrotechnics.
> through the 1920s, flash photography normally meant a professional photographer sprinkling powder into the trough of a T-shaped flash lamp, holding it aloft, then triggering a brief and (usually) harmless bit of pyrotechnics.
https://en.wikipedia.org/wiki/Flash_(photography)