Brazil was the last place in the Americas to abolish slavery — it didn't happen until 1888 — and that meant that the final years of the practice were photographed.

This has given Brazil what may be the world's largest archive of photography of slavery, and a new exhibition in Sao Paulo is offering some new insights into the country's brutal past.

One image at the exhibition, for example, has been blown up to the size of a wall. "Things that you could never see, suddenly you see," says anthropologist Lilia Schwarcz, one of the curators of the new exhibition called Emancipation Inclusion and Exclusion....