Picasa 3.0 comes with a Retouch tool, something like the stamp or clone tool you get from Photoshop or GIMP. While the latter software operate by taking a sample then applying to the intended area, Picasa’s Retouch works exactly the opposite. You point a brush to an area you want to fix, then pick other area to clone it.
The option for retouching is surprisingly very simple, allowing you to only adjust your brush size. Please take note that the max size brush is fixed, so if you use a 1920×1200 resolution picture, you have to expect that you brush would be smaller.
This is the original photo with the planet behind the Enterprise.
Behold, how I fade the planet from the photo!