The photograph above is one that I took in the Monterey harbor last year. For some time now, I have wanted to figure out how to isolate parts of a photograph, so that they are in natural color, while the rest of the photograph becomes black & white. I don't know that my method is the best or most professional, but I finally found a method that works for me. The photograph above is my first attempt.
One thing I have decided is that a computer mouse is not a good tool for this. It requires more precision than is possible with a mouse. If it is a technique I find myself using a lot, it would be worthwhile to invest in a graphics tablet.