Neue Photographische Gesellschaft

The "NPG" logo changed a bit during the years in its boundary (see the references below) but the actual letters NPG remained looking the same. Other logos used were a star and crescent and a flag with a star on it, see the TPA site.

The Neue Photographische Gesellschaft (NPG) was the first and biggest early producer of real photograph postcards. Arthur Schwarz (1862-1944) founded the company in 1894 in Berlin-Schöneberg, and there were later subsidiary companies in other countries. The company closed in 1921, although the NPG trademark and the postcard department were acquired by E. A. Schwerdtfeger and ran until WW2.
In 1908 NPG left the P.R.A. after which 1909 is the registration date in the logo.

NPG having been so big, there is plenty of information about it on the web. Here is a (German language) site dedicated to NPG. Here is a good account in English (TPA). A catalogue of cards 1-1000 of the initial series is being developed at rosspostcards.com/NPG.html.

NPG advert 1908

EXAMPLE CARDS HERE