New Post: Use +opaque option

The above example was not a real example.
What I need is to know if there is any option to change all the pixels that are NOT from one color to another color.
For example all the pixels of an image that are not green pixels become blue.

EJ:
Input
https://drive.google.com/file/d/0B8tYI098T34pcHVyei1JcGNaaVE/edit?usp=sharing
Output
https://drive.google.com/file/d/0B8tYI098T34pc25JT1l0ZFBoSU0/edit?usp=sharing

Thanks