Adjust image so it inverts colors

When creating documentation screen shots with dark or black backgrounds are hard to read on paper, and expensive to print. It would be nice to invert dark background to light and text to dark. For example terminal windows are usually balck on white text, invert colors so image is saved as white background and black text. Currently having to save images off and open them in Pinta to perform this action, Adjustment>Invert Colors.

Greenshot for Windows has this feature under left task bar makes it so easy.