MacBook Pro with Retina display VGA problem
To correct the resolution, open the Display panel in System Preferences, connect your monitor if not already connected, and look for the Display preference window on the projector.  Click on "Scaled" instead of "Best for display".  Then hold the Option (⌥) key while clicking again on "Scaled" and you will see a list of resolutions to choose from.



You can then select an appropriate resolution from the list.

To correct the color, click in the Color tab in that same window, and either choose from one of the available color profiles, or click the "Calibrate..." button and adjust the color as needed.