In the last few years, powerful images of police interacting violently with African Americans -- usually men, or teenagers, or even children -- have been on the news, all over the world. In these images, black men are getting shot or choked or hauled away in handcuffs. There are others too, memorial photographs from happier times: of young boys with plump cheeks or wearing graduation caps. Photographs of Eric Garner, John Crawford, Michael Brown, Tamir Rice, Walter Scott, Freddie Gray, Laquan