There is an option to enable a high-contrast view in OS X Mountain Lion. It is however, a global effect, so you can't modify specific regions.
To enable a high contrast mode:
> On the Dock, click Settings
> In Settings, click on Accessibility (System Section, second icon from right)
> Select Display from the list on the left side
> Ensure the Invert Colors checkbox is checked.
This setting will invert the colours on your screen:
Black becomes white, white becomes black, blue goes to orange, green goes to purple. I'm not sure if it's the solution you're looking for, but it should help you increase readibility in some cases.
If it does work for you, and you don't want to use it all the time, you can place a shortcut to the options in the menu bar:
> On the Dock, click Settings
> In Settings, click on Accessibility (System Section, second icon from right)
> At the bottom of the window, select the Show Accessibility status in menu bar checkbox.
Hope this helps you out!
- Callum