Whitepass, Probably a bit of both:
http://plate-camera.livejournal.com/
Now that my Internet connection seems to be working again, I had a really good look at the one posted by SR6900.
That photo, and maybe all the others has been reproduced using a printing process called DuoTone. It was and probably still is popular to enhance photos. The process really only works on sharp photos, and most paint programs have the process built in built in, or have tutorials.
The (printing) process camera operator took a standard black and white photo and produced a printing negative with microscopic dots running at 45%. He then made a second negative with the dots running at 15 or 20%. The first negative was used to produce a black printing plate, and the second was used for a colour. That was almost always blue, but sepia like the colour used in your prints was also popular.
Because everything had to be printed twice, the process was very expensive, but well worth it for art books, prints and postcards. I have a book called "Never On Wednesday" (The first decade of the Rio Grande Zyphyr) which is completely done in DuoTone.
If you fiddle with photos on your computer, try converting some to black and white, then converting them to duotones.
http://www.clubsnap.com/forums/showthread.php?t=322384
