I have just found this very nice program called Recollored that colorizes B/W photos. I was intrigued from the examples provided by the Program’s author so I downloaded the program to give it a try. Here are my results.
I started with this Sepia toned image
Then I drew a few lines with the colors I wanted my image to have
Et voila
Impressing to say the least, the results where much better than my expectations. Some parts ween’t colorized but that can be easily corrected with better brushing, keep in mind that this was my very first try using this program.
You can read more and see more examples here
Your colorization is really cool. My favorite stuff to colorize are photos of bronze statues. I used a much more laborized processed than the one you described. I once did it to a photo of a statue of Lucy that’s cast in bronze and sits in front of the Coffee Bean and Tea Leaf on Palm Canyon in Palm Springs. The photo made it to the cover of the local alternative paper, The Desert Post Weekly.
The forum post link is dead. I managed to find the program here.