Using basic photo editing software, you can take a digital photo and give it the look of a colorized black and white photo.
The way this works is that you take two copies of the same photo, one colored and one black and white. Put the black and white photo ontop of the colored one and then erase sections of the black and white photo so the colored photo shows from underneath.
1) Start with a digital photo or a good quality scanned photo.
2) In your photo editing program, adjust the saturation of the photo so your photograph goes from color to black and white. The saturation should say 0 or 0% or something along those lines.
3) Copy the black and white photo to your clipboard
4) Then, re-adjust the saturation of the original photo to about 50%.
5) Now, paste the black and white photo, from step 3, ontop of the muted photo.
6) Zoom in and use the erase tool to erase the sections of the photo that you want to be colorized.
7) Once finished, save your picture as a seprate file unless you want to replace the original.
Here are some examples of other colorized photos using this technique:
Original: Artichoke in bloom
Original: boy and bucket