Colorizing
Open the image you'd like to colorize
(I'm using a picture of Dan Aykroyd)
Select - Colors > Increase Color Depth > 16 Million Colors
Open the Layer Palette
Add a new layer
You can use default settings
Make sure Layer 1 is selected
Zoom in on the image
enough to outline the area to be colored
Now select the Lasso Tool
Carefully outline an area to be colored
With the foreground color of your choice fill the area
(His coat)
Do the same with the next area
(His shirt)
And again
(His face)
(If you need a fleshtone, here's the one I use)
(hold the Ctrl key to deselect the eyes !)
And again
(The background)
Once finished, on the Layers Palette change the Layer Blend Mode
It should be on > Normal
Change this to > Color
You should get something like this
Now select - Layer > Merge > Merge All (Flatten)
Colors > Decrease Color Depth > 256 Colors
And you can save it as a .gif image
or
Save as a full color .jpg without decreasing colors