The exhibit takes its name from one of the earliest forms of 19th-century photography - camera obscura - in which a dark, shadowy image is projected onto a screen. The resulting view is upside down and inverted - a perfect metaphor, in the opinion of the exhibit's curator, Pete Brook, for the distorted view too many Americans have of the skyrocketing number of inmates and what he calls the prison-industrial complex.
Brook, 33, a writer who now lives in Portland, Ore., developed a fascination with prison photography after leaving England eight years ago to write his master's thesis on California's San Quentin, the oldest operating prison on the West Coast.
"I wanted to look at a museum; it happened to be a prison museum," he said in an interview at the gallery, where the show runs through March 7.
By chronicling the experience of some of the more than two million U.S. inmates, Brook says his ambition with "Prison Obscura" is to bring citizens face-to-face with these images and to contemplate how prison proliferation has changed America.
He had a lot of ground to explore.
According to the Commonwealth Foundation, a conservative think tank, Pennsylvania's prison population has increased by 500 percent since 1980, to roughly 50,000 inmates, and the state lacks enough beds even after building 18 new prisons. Nationally, the U.S. incarceration rate is the highest in the world. With 5 percent of the population, America has 25 percent of the inmates.
The exhibit shows satellite pictures of the nation's more than 5,000 locked facilities, looking starkly similar with clusters of pods and units.
Most of the photographers tried to humanize their subjects.
A mural of photos and writings from men at Graterford - the state's largest maximum security prison - involved in the Restorative Justice Project with Haverford staff and students "gives voice to the guys who don't have a lot of opportunities to represent their perspective," said Kristin Lindgren, director of Haverford Writing Center, who oversees the program.
With 2.3 million inmates on a given day, the photos of smiling inmates in front of Christmas trees, mountains, the Statue of Liberty, or medieval castles make up their own genre of American photography.
In contrast, photos from a California class-action lawsuit claiming overcrowding and inadequate physical and mental health services show men stacked in triple bunks in gymnasiums, in cages used for mental health treatment, and other grim slices of prison life.
"If we're going to talk about images that change people's lives," said Brook, "then these crappy, low-resolution photos are those."