Washington - The Smithsonian American Art Museum marks the 30th anniversary of its photography collection Friday with a major exhibition of 113 works that reflect how the medium has evolved.

"A Democracy of Images" includes pictures by Ansel Adams, Diane Arbus, Walker Evans, William Eggleston, Robert Frank, Irving Penn, Annie Leibovitz, Edward Weston and Gerry Winogrand, among many others.

"Almost instantly (after its invention in France and Britain), photography was adopted as a technique that could do miraculous things, and as a new form of art," curator Merry Foresta said Thursday at a press preview.

Photography has been hugely popular with the public from the outset, she added, with "people standing in line to have pictures taken" upon the opening of the first photo studios in the mid 19th century.

"A Democracy of Images" runs through January 5.

For those unable to travel to the Washington museum - whose photography collection boasts 7,000 images - the full exhibit has been posted online at www.americanart.si.edu/photographs.