Michael Mandiberg has scanned photographs shot by noted artist Sherrie Levine in the late 1970s, taken of black and white documentary photographs of Depression-era Alabama sharecroppers originally photographed in 1936 by the legendary Walker Evans. Mandiberg has posted his digital photos, essentially reproductions of reproductions, on two Web sites he has created: AfterSherrieLevine.com and AfterWalkerEvans.com. The public is prompted to download and print Mandiberg's third-hand images along with a "certificate of authenticity" -- stating that the re-appropriated photographs are genuine Mandibergs. Printed out at 850 dpi, they have the same resolution as the Levine photographs, yet look almost exactly like the original Evans images. This conceptual work of net art forces us to question how we choose to value an image -- or not.