The Smithsonian National Museum of American History recently discovered these images, the first 3-D, color stereoscopic photographs of San Francisco after the 1906 earthquake. Photographer Frederick Eugene Ives took the color images, known as kromograms, six months after the magnitude 7.8 earthquake struck the city on April 18, 1906. The top pair of images show the Flood Building on Market Street. The bottom pair is a view of a street near City Hall, looking northeast.
Shannon Perich, associate curator of the museum’s photographic history collection, says Ives patented his color method in the early 1890s and explains that seeing the images in 3-D requires a step-shaped viewer called a Kromscope. You could try getting a feel for the three dimensionality by sitting from your computer at a comfortable distance and letting your eyes relax until you see a double image; then try to merge the left-right images together. Some additional tips to see the effect appear on Donald Simanek's Lock Haven University page, Martin J. Powell's page and digital-photography-tips.net.
Credit: Courtesy of the Photographic History Collections at the Smithsonian’s National Museum of American History