Leon Daniel was born in Romania and grew up in Germany, where he worked as picture manager at the Berlin office of Associated Press, the press photo agency. Celia Kutschuk (a Ukrainian émigré and aunt of the photographer Jerry Cooke) and Alfred Eisenstaedt also worked at Associated Press and the three knew each other before their emigration to New York. The German émigré Franz Furst, who arrived around 1936 to New York, was probably the picture agent of PIX (and later vice president).

Together with the Black Star, Rapho Guillemette, Modernage, Monkmeyer, European Picture Service and Three Lions photo agencies, PIX provided an important network hub for emigrant photographers and photojournalist who had fled Europe for New York. Located at 250 Park Avenue, PIX was close to the Black Star Agency and to the headquarters of such magazines as Life and U.S. Camera, and also close to Grand Central Terminal. This was an advantageous location as trains were an important and reliable means of transportation for pictures at the time. In addition to Eisenstaedt and Karger, PIX Publishing also represented the work of émigrés Josef Breitenbach, Fred Stein, Lilo Hess, Ernest Rathenau, Wolfgang (Wolf) Suschitzky, Otto F. Hess, Robert Capa, John Gutmann, as well as British-born Cecil Beaton and the Americans Nina Leen, Marion Post-Wolcott and Eileen Darby, and many more. Like Black Star, PIX charged fifty percent commission on the pictures they sold, as can be gleaned from the correspondence between Leon Daniel and Fred Stein. (As a matter of interest, in the late 1930s and early 1940s, an apartment rental in Manhattan cost between $50 and $150, depending on location, with $20 corresponding to about $300 in today's money.) The agency also provided work as darkroom technical assistants for newly-arrived émigré photographers still establishing their careers, as in the case of Werner Wolff.

In the 1970s the PIX archive was integrated with the Klinsky Press Agency collection and is now part of the huge collection of photojournalistic and press images located at the Gallery of Ontario.