To gain a better understanding of what you can do with Curves, here are some real world examples that will show you how to do a few common tasks with the Curves tool. Hopefully, this will spur your creative juices and allow you to take full advantage of Curves in your own project.
Bright skies and dark foreground is a common problem with many types of photography, especially when taking photographs in high-contrast situations. While there are many ways of darkening skies in Aperture, such as the burn tool, I personally always prefer to use the Curves tool as it gives the user more control over the process, and excessive use of the burn tool occasionally can cause some odd color shifts.
Select an image with the sky that you want to darken and carry out the following procedure:
Add a Curves adjustment from the Add Adjustment pop-up-menu in the adjustment tab of the inspector.
Start by reducing the brightness. Do this by adding a point in...