Reader Shmikey gets the prize... a genuine postcard! Just e-mail me your preferred snail mail address, Shmikey. I, too, knew it must be nineteenth century impressionism, but couldn't find the image. Kudos! You are truly a formidable internet sleuth.
The painter of the portrait in question in this post is (in Smikey's own words);
Armand Guillaumin, born: Paris - 1841 / died: Orly, 1927
He was critically praised and admired through his career, and was a major presence in the Impressionist movement, with close ties to Gaugin, Pissarro, Cezanne and Monet. He was never quite as famous, but is recognized as "one of the few artists that critics agree epitomise true classic impressionism"
How Bantam Books ended up confusing this with Friedrich's Traveler Looking Over the Sea of Fog is an even greater mystery, though I find the portrait fits the character of Dr. Frankenstein (not his creature)very well. He appears haggard and haunted.
Find out more about Guillarmin HERE.