Scientists at the Getty Conservation Institute (GCI) in Los Angeles have developed a new scientifically based method for authenticating historic photographs. Previously, the accepted method had been based on visual and microscopic inspection of images.

GCI's Dusan Stulik and Art Kaplan, along with photographic conservator Tram Vo, were able to identify hidden chemical signatures associated with the more than 150 different chemical processes that have been used to develop prints since photography began. Using spectrometric analyses, they found that photographic paper contains a unique combination of elements, most notably,  barium and strontium, that can determine who made the paper and when.

Recently, Stulik and Kaplan were invited to perform chemical analysis on Henri Cartier-Bresson's original photographs. This was part of the initial work needed to build an archival database for the photographer's existing prints, against which his other vintage prints could be compared in the future.