Painting?

This movie was just played on Universal HD, so I got a chance to see the painting you mentioned. It's called "The Raft of the Medusa" by Theodore Gericault, painted from 1818-1819. It's currently on display at the Louvre.

The painting depicts a hastily crafted raft built from the masts and boards of The Medusa (a French Frigate) after it sailed into shallow water four miles off the coast of Africa in 1816. There were not enough lifeboats to carry all of the passengers aboard The Medusa, so the captain ordered that the raft be built and the lifeboats would tow it to shore.

It quickly became apparent that they'd be unable to tow the cumbersome raft all the way to shore, so they cut ropes and left the men on the raft to fend for themselves. After 17 days of drifting, the ship The Argus discovered and rescued the remaining survivors. It was revealed that 20 men had been murdered and thrown over the first night, and after only 6 days, men had resorted to cannibalism.