根据Paint.Net "The Pleasantville Effect"做的效果
步骤如下：(the original link came from Paint.Net "The Pleasantville Effect", I added one extra step-6)
1.Choose the Magic wand tool.
2. I usually turn the tolerance down a bit, 50% Will select too much on most images(I used 27% for the flower).
3. Select all of the area of the image that you want to stay color.
4. Copy that area and paste it into a new layer called color layer.
5. next Deselect the selection with ctrl+D.
6. 万一有多余的部分被选中，可用橡皮擦把多余部分擦掉. In case there is more than you want had been selected/coped/pasted, you can use Eraser to remove it.
7. now choose the background layer.
8. Then Goto Adjustments and click black and white.
9. Now merge the two layers.
10. Use the curves tool and edit the luminosity after mergeing the images to make the image seem more realistic. You can also add glow to add vibrance to the image.