"He also ran a nude photography studio which welcomed blacks and whites!!"
That passage describes Frank Marshall Davis' early days in Chicago and referred to Davis. Do you suppose he was the photographer for the Naughty Ann pictures? Got her drunk, sexualized her, and then took the photos? Those photos were not taken with a Brownie. They have a professional air to them.
Furthermore, if he had taken those photos to the local drugstore to be developed, he probably would have been arrested. So, he most likely developed them in his own dark room, or he had a friend in the photography business who would develop the film on the sly.