It was a long time I was looking for Color Accent software because all the Canon cameras I got, don’t have Color Accent feature. Today I found it, but it is for windows users only. I hope to find something similar for Mac. Before this tool, I used to apply black and white to the whole photo, and used redo brush to get back colors on the portion selected. I will continue to use that method only for multicolor subjects, but for one color or color range it is faster the tool below.
Install Paint.Net and this set of filter from Kris Vandermotten in which you can find Color Accent. Just use the tool “Pick a Color” and apply the effect “Color Accent” pressing the arrow button or adjusting levels manually.
I have uploaded some samples on flickr (look at the window on the right) and I’m sure I will use this tool a lot.